[[quoteright:346:[[Webcomic/{{XKCD}} http://static.tvtropes.org/pmwiki/pub/images/Extrapolating.PNG]]]]
[[caption-width-right:346: [[AltText By the third trimester, there will be hundreds of babies inside you.]]]]

->''"There are three kinds of lies: lies, damned lies, and statistics."''
-->-- '''Benjamin Disraeli'''

It has been generally demonstrated that, because human brains are wired toward pattern detection, we are lousy at intuitively interpreting statistics; this is the main reason why casinos are viable businesses. Trying to do anything to curb this problem often results in the worship of the RandomNumberGod, or beliefs like:

* '''The hit/miss belief''': "A hit ratio below 25% is hopeless and a hit ratio above 75% is guaranteed. Everything else is a crapshoot." In reality, not so much. There are four groups of 25% in 100%, so there is a 1 in 4 chance of hitting any one of them.
* '''[[GamblersFallacy The Gambler's fallacy]]''': All probabilities should somehow "even out" while you're playing. For example, if the computer has a hit chance of 50%, and hits, that's okay. However, if it then scores another hit right away, TheComputerIsACheatingBastard. In truth, it just happened to be the way the "dice" fell. As is often stated, "dice have no memory."
* '''Naďve Combination of Probabilities''': Given the probabilities of two events, people will often simply either add them or multiply them. Generally speaking, calculating the combined probability is much more complicated. For example, suppose you roll a die twice. The probability of a six is 1/6 each time, so the probability of at least one six in two rolls must be 1/3, right?
* '''The Definition of Probability''': There's two ways probability can be defined. The first is what should happen in a random process ''in the long run''. The second is the degree of certainty with which a belief is held. The first definition applies to statements like, "The probability of rolling a six on a fair die are one in six." The second applies to statements like, "My favorite team will win this game." This difference can be very important. These two views are called frequentist and Bayesian, respectively.
* '''Decision-Making and Probability''': Many make a mistake related to all these fallacies. When a decision-maker makes a decision to play the odds in a situation where he can calculate the odds, he's taking a measured risk based on what he knows at the time. This is his best decision based on what he could possibly know at the time. If this fails, calling it a ''wrong'' decision is fallacious because it would require knowing the less-likely alternative would happen. For example, if two gamblers agree to roll a fair die, betting 1:1 where Gambler A wins on a 1-5, and Gambler B wins on a 6, Gambler B is making an idiotic decision to bet - and the decision remains idiotic even in hindsight if he wins.
* '''Even Probability Distribution Fallacy''': When someone assigns equal probabilities to a list of possible events where an even probability distribution cannot be presumed: "The suspect either shot the victim or he didn't shoot the victim, therefore there's a 50% chance he shot him." Ad Absurdum, one would have to claim that you have a 50% chance of winning the national lottery because you either win it or you don't.
* '''Projecting From a Small Sample Size''': Even a fair coin has a significant probability of coming up heads seven times in ten flips, so you can't project from such a trial that the coin has a 70% probability of coming up heads.

Note that while this often makes fun of the developers messing up at statistics or the author having no clue how it works, this can actually be invoked or justified.

Also see TwentyPercentMoreAwesome, which involves quantifying the unquantifiable.

!! Examples of how this plays out in storytelling:


[[folder:Card and Dice Games]]
* It's common for a naďve poker players to (correctly) fold a bad hand, such as flush draw with no other outs, to a large bet, only to lament their "mistake" when it turns out their hand would've improved on the turn or river. Especially naďve players may try to "correct" their mistake by calling the next time they find themselves in a similar situation, which more savvy players can exploit.
* In TabletopGame/{{Monopoly}}, you may decide to build houses when you see your opponent will land on your monopoly a throw of 6, 7, or 9 on two six-sided dice.[[note]](This is not an error: no monopoly on a standard Monopoly board is spaced so you would land on it on a 6, 7, or 8, though if there were one, it would have higher odds than the above combination.)[[/note]] Anyone with half a clue as to how the game works and basic probability theory realizes that's about as lethal a situation as your opponent could be in (for a single monopoly), and would build. Yet if your opponent throws a 12, and bypasses your entire trap, your decision was just as reasonable as before. It just didn't pan out.
* Many TabletopGame/{{Bridge}} players feel that the computer-generated hands used for many duplicate games are more unusual (i.e. favor more unlikely distribution of cards) than human-shuffled hands. They're right, but in a backwards way: The computer-generated hands are ''more likely to be completely random'' than hands dealt from a human-shuffled deck. Even the best human-shuffled deck will retain a few cards in the same relative order as they were played in the last hand; computer-generated hands don't (except at the frequency you'd expect from random chance).
* Many players of the online version of ''TabletopGame/MagicTheGathering'' are convinced that the algorithm used to shuffle players' decks is flawed and biased. Some say the bias is towards "mana flood", where you get too many mana-producing cards (and not enough spells to actually use that mana with), while others say towards "mana screw", which is ''the exact opposite'' -- not getting enough. In reality, the algorithm is completely incapable of either, since it does not consider what type any given card is when performing the shuffle. The reason for the dissonance between physical and online play (when there is one at all -- mana screw and mana flood are common on cardboard too) is that having to physically shuffle a deck enough to provide a truly random distribution every time would be ''incredibly annoying'', particularly given the number of times some decks end up being shuffled in a single game. Most people just take their land cards, which end up all in one pile at the end of a game and put them into the deck at fairly even intervals to avoid there being giant clumps of nothing but land. For practical reasons, even in tournaments it's accepted that the deck doesn't have to be truly randomly distributed -- it just needs to be random enough that a player can't predict what comes next.
* Go to any online TabletopGame/{{poker}} forum and look in the General Discussion forum. More often then not, you'll find a sticky about the game not being rigged, and an explanation of why it may seem that it is. Most forums will also have a 'Bad Beats' section for whining about the 'rigged' play screwing the loser.
* One popular roulette strategy (called [[http://en.wikipedia.org/wiki/Martingale_(roulette_system) Martingale]]) is believed to always net you money. The same strategy works the same on any 50% chance double money back bets (or as long as the chance to win is balanced against the payout). The basics of the strategy is to bet 1 on red/black, odd/even, or high/low when you start and if you win, and double the bet if you lose.[[note]]For example, losing three in a row then winning means betting 1, 2, 4, 8, which means you've lost 7 and won 8, with a net profit of 1.[[/note]] The belief is that you will eventually win, and thus win the initial bet.\\
There are a few reasons why this doesn't work:
## To be guaranteed a win, you'd need an infinite amount of money and time.
## Real casinos always have betting limits, which remove the option to double up at some point.
## If your original lost bet is one dollar and you follow this stratagem, an unlucky streak of ten consecutive losses has you betting $1024 to chase after your original loss of a ''single dollar''. Even if you do win, all you get is your original dollar back. You were better off just betting one dollar at a time and hoping for a winning streak.
## All bets in any commercial gambling organization have a house advantage, meaning you never have a true 50% chance of winning.
* There is an optional "Event Deck" for the board game ''TabletopGame/SettlersOfCatan''. Using it instead of the dice makes probabilities "even out" somewhat (going through most of the deck before reshuffling guarantees that each number will come up about as often as it "should").

[[folder: Comic Books]]
* In the ''ComicBook/{{Asterix}}'' album ''The Soothsayer'', the Roman Empire tasks a centurion to round up all prophets and soothsayers in order to suppress pagan beliefs. A conman passing himself as a soothsayer gets caught and is given a test to see if he can predict a roll of two six-sided dice. He breathes a sigh a relief as he knows his luck is usually awful, and picks (stupidly, statistically speaking) seven, which just so happens to come up on the dice and "prove" him the real deal. He goes on an InsaneTrollLogic demonstration that he picked the right number ''because'' he can't tell the future. The centurion isn't convinced until the soothsayer mentions that the villagers believe anything he tells them, which makes the centurion offer to let them go if he convinces the villagers to leave.

* ''Discworld/TheScienceOfDiscworld'' books have an arguably accurate but somewhat twisted take on statistics: the chances of ''anything at all'' happening are so remote that it doesn't make sense to be surprised at ''specific'' unlikely things.
* DaveBarry once joked that he always flew on the airline with the most recent crash, on the assumption that it wouldn't be "due" for another one.[[note]]This could have some validity if you assume that the airline with the most recent crash would be under the most scrutiny and thus have the most reason to tighten up their safety standards, but it's not valid for the reason he (jokingly) gives.[[/note]]
* MarkTwain's ''Life on the Mississippi'' contained the following proof of what you can do with statistics:
--> In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo[[note]]Illinois, not Cairo, Egypt[[/note]] and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
* In Creator/LoisDuncan's ''Literature/AGiftOfMagic'', the psychic protagonist, Nancy, is given a standard test to detect telepathic abilities. She is asked to pick, without looking, all the white cards out of a deck of cards filled with an equal amount of black and white cards. Because she wishes to hide her ability, she picks all the black cards so that she would get all the "wrong" answers and fail the test. The examiner sees right through Nancy's ploy because there is an equal probability of picking only white or only black cards and explains that if she really wanted to screw up the test, she should have picked a roughly equal amount of black and white cards at random.
** That might not have helped. People are ''horrible'' at generating random numbers, so even if she picked equal (or near-equal) numbers of black and white cards, a more sophisticated analysis of her picks would reveal what she was doing, most likely by identifying a lack of runs of a single color (see fallacy #2 above). It might ''delay'' the recognition of her ability, though...and unless it were ''blatantly'' obvious what she was doing, it might leave enough doubt to prevent others from being certain.
** The ''best'' way for her to deceive the examiner would be to not even bother to ''use'' her ability during the session, but merely pretend to concentrate while drawing the cards blindly.
* ''Literature/TheMoonIsAHarshMistress'': The supercomputer Mike calculates the odds of a plan's success as a whole. At the successful completion of each of the early steps of the plan, Manny asks him for an update on their odds from that point, and Mike keeps giving odds ''lower'' than they were before, saying that the later steps in the plan have more opportunities to go wrong. However, these late opportunities for failure (which he was always aware of) should have been factored into every single odds calculation from the beginning. Each successful step should only improve the plan's chance of success from that point.
* Creator/BrianAldiss wrote several stories where humans are near extinction, and where society thus makes heavy use of robots; one characteristic of such robots is that their logic often leads them to mistake clear reasoning for correct reasoning. One such story has this exchange:
-->"There is more country than city."\\
"Therefore there is more danger in the country."
* {{Discussed}}, {{subverted}}, and {{justified}} in ''Literature/TheWheelOfTime'' book ''Towers of Midnight,'' when Noal Charin points out to Mat Cauthon that rolling dice to determine which direction to go won't work, due to the higher likeliness of rolling odds than evens, and Mat counters that his magic luck means that it wouldn't be random, regardless.
* Just before Princess Diana gave birth to Prince Harry, one British newspaper article claimed that if the unborn child was a boy, that would complete a sequence with a "1 in 60,000" probability, and therefore it was overwhelmingly likely that the child would be a girl. This ignored the fact that a sequence of 15 boys followed by a girl has exactly the same before-the-fact likelihood of 1 in 65,536 as a sequence of 16 boys (or of any other specific sequence of 16 births), and that this is because the likelihood of any given baby being a boy is about 50%, regardless of previous births (especially if not births by the same mother, as in this case).
* One book on recreational mathematics described "the college bet", so-called because its inventor supposedly made enough money from it to put his son through college. If you select three card ranks randomly, and then draw a card from a fair 52-card deck, the chance that it will be one of your ranks is 3 in 13, right? Thus (the book claimed) if you draw three cards, the chance of at least one being one of your ranks is 9/13 (0.6923), and with four cards this rises to 12/13 (0.9231). If the author of the book had followed this "logic" a bit further, he would have seen that this gives the chance of one in five cards being one of yours as 15/13, or more than certain -- which is clearly nonsense. (In truth, if each card draw is independent of the others (that is, the card is replaced and the deck shuffled after each draw), the three-card probability is 2170/2197 (0.9877 -- substantially better than the naïve calculation), the four-card probability is 28480/28561 (0.9972), and the five-card probability is 371050/371293 (0.9993).)

[[folder:Live-Action TV]]
* A high school science teacher on ''Series/TheDailyShow'' [[http://www.thedailyshow.com/video/index.jhtml?videoId=225921&title=Large-Hadron-Collider thought there was a 50/50 chance]] of the LHC creating a black hole and causing TheEndOfTheWorldAsWeKnowIt. His rationale? It could happen, or it couldn't happen, therefore there was a 1 in 2 chance of the apocalypse. ArtisticLicenseNuclearPhysics is also involved. Correspondent Creator/JohnOliver, who was conducting the interview, then suggested that he and the teacher try to breed after the end. The teacher replied that this was impossible, as both were male, but Oliver insisted it would either happen or not happen, a one-in-two chance!
* In the ''Series/CornerGas'' episode "Security Cam", Karen figures that there's a 50% chance of a riot breaking out in downtown Dog River, using exactly the same reasoning.
* On ''Series/TheOReillyFactor'', Bill O'Reilly argued that life expectancy was lower in the US than in Canada because the US has ten times as many people, and therefore has ten times the [[http://mediamatters.org/mmtv/200907270052 number of accidents.]]
* A common mention on the show ''Series/HellsKitchen,'' as well as a number of other reality shows, is that at any given time a given contestant has a 1 in X chance of winning the grand prize, where X is the number of remaining contestants. Not only does this suggest that the winner is chosen at random (which is not the intent of the statement), but also that every contestant is equally likely to win. This is untrue, especially on shows which have a number of obvious dud contestants (such as ''Hell's Kitchen'').
* Wrestling commentators discussing multi-person matches frequently claim that the champion in a 4-way match only has a 25% chance of retaining his title, with no regard to comparative skill levels or possible alliances between the participants. Given the fact that the outcomes are always predetermined, however, neither skill nor chance really has anything to do with it.
* In the ''Series/LawAndOrder'' episode "Coma", [=McCoy=] tries to ease Kincaid's conscience about subjecting a comatose victim to a high-risk surgery in order to remove a possibly trial-winning bullet. Subverted in that he's perfectly aware that it's bad statistics.
-->''"Well, I see one of three things happening: she gets better, she gets worse, she stays the same, and we get strong evidence. Two out of three ain't bad."''
* Invoked in ''Series/{{Survivor}}'' - As the players in the game dwindle, Probst tells them that they have a "one in ''x'' shot at winning the million dollars." The way he mentions this, it sounds like the winner of challenges (and at the game ''period'') is chosen at random, when it actually isn't. You can argue that if you're in the final six with TheLoad and someone who the jury ''hates'', you would have a one in ''four'' shot since the jurors would not vote for them. Justified in that he [[FridgeBrilliance does this to motivate the players]] and it's part of his "character."
* The Creator/FoxNewsChannel's fondness for flashy graphics to engage the viewer's attention occasionally lends itself to a few mistakes. Such as [[http://pics.blameitonthevoices.com/112009/fox_news_math_fail.jpg a pie chart where the total breakdowns add up to 193%]], or [[http://www.mathfail.com/scientists-poll.jpg this poll with a breakdown that adds up to 120%]]. Either with the pressure of the rush to get on-screen information ready by showtime, those responsible have little time to double-check their work; or [[TheyJustDidntCare they care more about making a quick impression on the viewer than ensuring accurate information]].[[note]]If the people polled can pick more than one option, poll results can easily add up to more than 100%. The first poll might be such a case, but a pie chart is a poor choice for showing that kind of data. The second poll suggests someone was stupid, whether the people who made the graphic, the people who calculated the numbers, or the people who voted for more than one mutually exclusive option.[[/note]]

* This is how synchronization (most notoriously of ''Film/TheWizardOfOz'' with ''[[Music/PinkFloyd Dark Side of the Moon]]'') "works"; the brain notices the few dozen coincidences and goes "oh wow" at them, whilst ignoring the thousands of non-coincidences which surround them.

* ''Theatre/CoxAndBox'': In the (sometimes cut) gambling number, the titular characters roll nothing but sixes on their dice, leading them to suspect the other is cheating. Although they both ''are'', no dice-weighting is quite ''that'' good.
* Deconstructed in ''Theatre/RosencrantzAndGuildensternAreDead''. A coin flipped 85 times comes up head each time, and they try to figure out how it's happening. Two explanations Guildenstern develops are divine intervention and random chance. The ultimate reason is that [[MetaFiction they're characters in a play]], so the author is making it happen.

[[folder:Tabletop Games]]
* Players themselves sometimes fall afoul of the gambler's fallacy.
* ''TabletopGame/{{FATAL}}'' says that to determine the probability of an event, you roll two percentile dice[[note]]That's a 100-sided die, or more commonly two 10-sided dice with one representing the tens digit, for non-gamers[[/note]], and if the second one is equal to or greater than the first, you succeed. That means that everything has a flat 50.5% chance of happening. And yes, you're supposed to do this for '''anything''' that doesn't have a specific rule for it.
** ''TabletopGame/WorldOfSynnibarr'' also does this.
* ''TabletopGame/{{Warhammer 40000}}'': Fears of "bad dice" abound. The previously mentioned lack of even distribution and the tendency of rolling methods to influence the result only adds fuel to the fire.
** Bad dice can be a real thing. Las Vegas maintains a very strict policy for evaluating the balance of dice BEFORE they go into a game, and replacing them at regular intervals. As most 40k players play with cheaper, mass produced dice, and will rarely replace them unless they have visually obvious defects, it is perfectly plausible for a player to be using biased dice.
* ''TabletopGame/BloodBowl'': There's always at least a 1 in 6 chance of succeeding or failing because ones always fail and sixes always succeed. Players hate this because you tend to fail at the worst possible time. Failing also ends your turn in most cases, so superstition abounds.
* In the ''Literature/ASongOfIceAndFire'' roleplaying system, there is a table for rolling random events in your family's history. This would be perfectly fine, except that you roll three dice for the events (thus making the events in the middle more likely) and the table is in ALPHABETICAL ORDER. Thus, Doom (the worst thing that can possibly happen to a family) is more likely than a mere Catastrophe (still bad, but not even half as bad), just because Doom is closer to the middle of the list than Catastrophe is. [[CrapsackWorld The results are very true to the setting.]]

* MMO players, almost without fail, will adhere to mindset two - they will notice the streak of resists/misses/landed enemy attacks/what have you that killed or almost killed them, but never notice the long, long, long string of hits that precede it. Any and all MMO forums will have a topic pop up fairly regularly asking whether (or sometimes screaming loudly even with no evidence to that effect other than they had a string of bad luck) the RNG is broken.
** ...which can lead to [[VideoGame/FinalFantasyXI no small confusion]] at times.
** This kind of fallacious reasoning reached memetic proportions in the pre-expansion VideoGame/WorldOfWarcraft encounter "Onyxia's Lair." A player who'd run into a string of bad luck assumed that the developers had made the encounter harder, and loudly complained: "She deep breaths more!" (Not breathes, ''breaths''.) Today, "She deep breaths more" is the official name of an in-game achievement you can earn in Onyxia's Lair.
** To further complicate things, some [=MMOs=] actually ''do'' use a skewed RNG, precisely because true randomness could, in theory, result in a string of misses one real day long, or the opposite. Since [=MMOs=] rely on a very ''predictable'' form of randomness (e.g., no plucky level 1 can be able to beat a level 20 monster because the monster miraculously rolls no hits, but if attacking a level 4 he must be able to win through pure luck some of the time), various measures can be put in place to make sure the game generates the good, reliable sort of random.
*** The biggest place this tends to show up is in loot drops, in order to ensure that a player gets loot AT LEAST so often. This is actually very important for helping to maintain addiction.
*** Because of players complaining about this, the drop rate formula for quest items was changed to ''increase'' the drop percentage every time the quest item required ''doesn't'' drop and reset it after one ''does'' drop. This is also to avoid the wild variation in time a quest can take when it's truly random. The formula for non-quest-related gear drops, however, is still truly random and doesn't vary from one attempt to the next.
** The players' failure to get how probability works was joked about in the 2015 April Fool's Day patch notes, which presented a large number of fictional changes to the game, one of which was:
--> The S.E.L.F.I.E. camera mission "Field Photography" is not appearing for all players due to its random nature. We didn't change anything; we just wanted to point out what random means.
* All ''Franchise/FireEmblem'' games after the fifth display inaccurate hit/miss percentages. The game actually uses the average of two random numbers to determine a hit, so a 75% chance to hit is really 87.5%. This system is likely in place to make [[FragileSpeedster dodging-type]] units evade more (and thus more viable) and high-accuracy characters strike more and lessens the chance that such a character dies ([[AntiFrustrationFeatures Due to permanent death and limited saving, this means restarting the entire level in most games]]) against all 3 of the random mooks that has a 2% chance to hit each.
** To prevent SaveScumming abuse, the tenth game's (unlike the ninth's, which was completely random) bonus experience system [[note]]EXP that may be freely given to any unit between levels, helpful for raising MagikarpPower characters, getting that precious extra level of stats ups or helping the guy lagging behind[[/note]] will ''always'' increases a character's 3 stats with the highest growth rate (Has an x percent chance to raise this stats on every level up). This wound up making it ''more'' broken, as some units quickly hit the {{Cap}} on their main stats (Aran), causing stats that would other almost never grow to suddenly increase at insane rates.
*** It is less broken and more "different". Bonus experience in the game should never be spent levelling characters without maxed stats[[note]]nearly all characters who have not hit a cap will have an overall stat increase averaging over 300%, or ''more'' than 3 stats on average[[/note]], but instead should be used to level characters who have already hit the caps on their main stats, resulting in hoarding and struggling a bit to get through the levels, followed by a sudden rise in level to the maximum amount when they finally hit that point at which using bonus experience is optimal.
** Starting with the tenth, if a character does not get at least one stats increased during a level up, the game rerolls (unless a character has hit the cap on everything). Starting with the eleventh game, a character's growth rates will be boosted or dropped if they are behind or ahead of the "average" stats. Like the main example, this helps deal with the ''very'' annoying chance that a character gets "RNG Screwed", except this is enough to force a restart on a ''file'' in some cases.
* WordOfGod to the contrary, most players of ''VideoGame/PuzzleQuest: Challenge of the Warlords'' believe that the game "nudges" all sort of random stats in its own favor. As many people complain about the computer's habit of chaining together 4/5 gem combos and extra turns, it's even more blatant in Spell Resistance, where an opponent with 2% resistance across the board will block approximately 15% of spells. The player, with the same stats, will be lucky to block one spell in hundreds.
* This trope is often brought up in {{MMORPG}}s, where many players believe that item drop rates can be mathematically calculated to determine how many monsters you must kill until you "should" find said item, by assuming that a 1% drop rate means that after you've killed a hundred, something's wrong if you haven't gotten one.[[note]]It is possible to calculate the probability of getting a drop in the first X kills, using 1-((1-n)^X) where n is the drop rate. By this calculation, you have a 63.4% chance of getting the drop after 100 monster kills at a 1% drop rate--about 2 in 3, which is high but far from guaranteed. The more kills you get, the higher the overall percentage, but unless there is a mechanic that forces a drop at some point, or the drop rate is already 100% or greater, a drop will ''never'' be guaranteed.[[/note]]
* ''VideoGame/CityOfHeroes'' actually has a mechanic called the "streakbreaker" that behaves like the second part. For a given base percentage chance to hit, if a player or mob misses a certain number of times in a row, the next hit is guaranteed. For a hit chance below 20%, you have to miss something like a hundred times in a row, but for hit chances above 90%, it only takes one miss to get a guaranteed hit on the next attack. If you were paying REALLY close attention, you could use this to ensure that a key attack doesn't miss.
* ''VideoGame/DungeonFighterOnline'' has a dice roller that is perfectly random for the first instance of every sequence (first upgrade attempt, or random item pickup, or something similar), but then often produces identical results for the next several sets (Failing an identical upgrade five times in a row, the same player getting every single item in a dungeon). It often "corrects" itself and skews the other way until results are even. The hit/miss ratio is the same, either producing a lot of hits or a lot of misses in a row, only rarely looking like the actual statistic.
* The ''VideoGame/{{Tetris}}'' Guideline has mandated that all Tetris games since around late 2005 have an implementation to make the gambler's fallacy actually happen (and make players complain less of being screwed by the [[RandomNumberGod RNG]]): Instead of rolling a D7 to select a piece, newer Tetris games take a sequence of all seven pieces and deals random permutations of it. Thus, after every seventh piece, all seven have appeared with equal frequency. This also makes every seventh piece completely predictable.
** Prior to that, the ''VideoGame/TetrisTheGrandMaster'' series also had an algorithm to make the gambler's fallacy come true: The game rolls six times (four in the first TGM) and takes the first result that isn't identical to any of the four most recent pieces dealt. It's still possible for this to "fail" and give you the same pieces over and over again since the game only rolls a fixed number of times; it's just much less likely than with a simple RNG approach.
*** The Tetris piece-picking algorithms are many and varied. One, the appropriately named Bastet[[note]]"[=BAStard TETris=]"[[/note]] system, [[SpitefulAI picks the worst piece possible for your current situation with an 85% accuracy.]]
* ''VideoGame/{{Civilization}}'':
** Ask anyone who's played ''VideoGame/{{Civilization}} IV'' (''especially'' those who play mods like ''VideoGame/FallFromHeaven'') and they will tell you that any combat with less than 80% odds is suicidal and should be avoided at all costs [[note]]though this isn't purely for the chance weighting, as it affects how much your unit gets damaged; combined with the AI favoring large stacks of weak units, this means your unit will likely die next turn[[/note]], unless the odds are 1% or worse, in which case victory is surprisingly possible (see Spearman v. Tank).
** Alleviated somewhat in ''V'', which is kind enough to give you all of the information BEFORE you attack and provides a rough estimate of where the forces will end up in strength after the round of combat. It was actually criticized heavily for its near-perfect accuracy in prediction! Later patches actually made it a bit more random.
** Not helping matters is that whoever wrote the code for battle predictions fell into this trope themselves. Due to the calculation failing to take several important factors into account, the result varies from "close enough to make a judgment call" to "no connection to what will happen whatsoever." See the ''Civilization'' folder under TheComputerIsACheatingBastard for the details.
* This trope is hugely responsible for the ''Franchise/{{Pokemon}}'' entries on TheComputerIsACheatingBastard, and is the number one thing the game's professional players complain about to similar levels of usage.
** In a more topical instance, players have a random 1/8192 chance of finding an alternately colored Pokémon, similar to albinism and what not. Many players only encounter one or two in several years of playing, others never find one, and some find them with surprising regularity.
** In a similar way, the Pokérus (a "virus" that doubles a Pokémon's stat growth) has a 3/65,536 chance to be on a Pokémon, or 1/3 the probability of finding a "shiny" Pokémon. Many players have never seen the Pokérus, while a few have been lucky enough to get it more than once. Once you have a Pokémon with the Pokérus, though, it's very easy to spread it around the party.
** The first generation did have statistical errors due to bugs, such as attacks that should never miss actually having a 1/256 chance of missing due to the code using "less than" checks instead of "less than or equal to" checks.
*** Similarly, the "absolute guarantee" of the Master Ball catching a wild Pokémon is not; there is an incredibly small chance it will fail when used, but luckily hasn't happened yet.
*** Fortunately, this only applied to the first generation of games. After that, it bypasses the catch calculator entirely.
* ''VideoGame/FinalFantasyTacticsA2'': many people report that attacks that give a 95% success rate fail often. It seems likely that this is the case given the number of complaints (especially since the previous game didn't have these problems - then again, the previous game had an actual flaw in its RNG where success rates tend to be universally higher than the shown numbers suggest) but obviously it's impossible to say for sure.
* ''VideoGame/XCom'':
** ''{{X-COM}}'''s accuracy reports during combat aren't exactly blatant lies, but they're not exactly accurate, either. What ''X-COM'' does for a hit check is up to two rolls. The first is done against the accuracy check, and if it passes, you automatically get a dead-on shot. The other roll, if the first fails, is the deviation from where you're aiming, which may also end up being nil, resulting in a dead-on shot. So that 75% Accuracy the game reports? More like 77% to hit the target you're aiming at, and up to around 20% to hit someone else, resulting in somewhere around a 86% (on average) chance of someone getting hit by any given shot in a heated battle. Oh, and 100% accuracy reportedly doesn't exist.
** ''VideoGame/XCOMEnemyUnknown'' ditches this in favor of telling player straight how likely he is to hit. However, many players insist that the game cheats in favor of aliens on higher difficulties and Classic mode. This eventually got so bad, that the [[http://www.schwanenlied.me/yawning/XCOM/XCOMPRNG.html RNG was taken apart for testing]] by the community... and found to be 100% correct. As it turns out, on the lower difficulties, the computer actually cheat for the ''player''. Thus, once the aid is removed on the higher difficulties, players feel cheated when their "sure" shots no longer hit all the time.
* ''VideoGame/JohnMaddenFootball'':
** The MaddenCurse works this way. Generally, the cover is awarded to some athlete who just had a phenomenal season. The next season, the player is often beset by the sorts of bad luck that befall all athletes (injuries, bad games, etc) except they receive more attention. In some cases, it may also be a SelfFulfillingProphecy if the player gets a big ego and skimps on workouts, or if other players are more motivated to play hard against him. But mostly it's just that any season of a player is likely to be average (for his or her capabilities) and any season which leads to feature a player in games or magazine stories is likely to be way above average, so it's just a good chance of a "dice roll" showing a lower number, just like the next number after you rolled a six on a normal die is likely to be lower than that. The technical name for this is [[http://en.wikipedia.org/wiki/Regression_toward_the_mean regression toward the mean]].
** A great example of this would be Brett Lorenzo Favre's appearance on Madden. It appeared that Favre had subverted, nay, broken the Madden curse while playing for the New York Jets. Then the Jets lost four straight games and a bid for the playoffs. "What went wrong," you ask? Brett Favre played the last month of the season with a torn bicep in his throwing arm and no one did anything about it.
** A more direct example are the year-in, year-out complaints that either the stats or the on-field experience are unrealistic, by pointing to the raw numbers. Since ''VideoGame/MaddenNFL'' is a video game, the developers have to shorten the quarters because most gamers aren't willing to invest multiple hours on a single game. So ultimately this means that gamers are running between 50-70% as many plays as a real NFL contest. Yet many expect to produce as many points or exciting moments, while somehow maintaining realistic results on a per-play basis. This is mathematically impossible. EA chooses the former, heavily slanting the game in favor of the offense, which has caused somewhat of a BrokenBase amongst fans of the series.
* In a strange twist, ''Final Fantasy VII: Crisis Core'' had the DMW, a slot-machine of various character faces that spins during combat, creating different effects. The only way to level-up is for three "7"s to align. Isn't that awful?!? Leveling based on total randomness?!? Except...it isn't. The manual ''lies''. The DMW is actually controlled by an ''insanely complicated'' mathematical formula that, in-game, manifests itself as the strange impression that chance always ''just so happens'' to work out exactly the way natural progression should. In essence, one in a million chances succeed nine times out of ten. Furthermore, while it's not shown anywhere in the game, enemies actually do give experience when killed, increasing the odds of hitting the combination that gives Zack a level up. As can be expected, this means that getting 2 or more level-ups in a row or shortly one after another can only happen if you've been under the effects of Curse status which disables DMW for an extended perioid of time and killed a ton of enemies during that time and if you kill enough enemies, you're eventuallly guaranteed to get the combination that gives you a level up.
* The programmers of ''VideoGame/SidMeiersAlphaCentauri'' fell afoul of this trope when they wrote the code to estimate the battle odds displayed before a combat: they used an obvious-but-wrong method of working out chained probabilities, leading to the game tending to grossly underestimate the actual odds of victory. For example, a strength-8 unit with 30 hitpoints attacking a strength 8 unit with 10 hitpoints would be shown as having a 75% chance of victory; the actual odds of winning are 99.93%. Under the right circumstances, this could result in the game predicting a one-in-a-million chance of winning, when the actual odds are 90%.
* In ''VideoGame/{{Achaea}}'', you can flip a coin. Some players argued that the chance was approximately 60/40, rather than the expected 50/50. However, after careful study of the game code, one developer found out that the players were actually right, and corrected the programming error, while also claiming that it wasn't impossible to have the coin fall on edge.

* ''WorldEndEconomica'' has the protagonist, who is a little full of himself, apply the Gambler's Fallacy to trading on the stock market.

* In ''Webcomic/DarthsAndDroids'', Pete (R2-D2) likes to "[[RandomNumberGod pre-roll the ones out]]" of his twenty-sided dice. He takes a huge number of dice and rolls them once each, and selects the dice that rolled a one. He rolls those dice again, and selects the dice that rolled one a second time. Since the odds of any given d20 rolling a one three times in a row is 1 in 8,000, another roll of any of these dice has only a 1 in 8,000 chance of rolling a one again, right? ... No.
* ''Webcomic/AwkwardZombie'' addresses the matter [[http://www.awkwardzombie.com/index.php?comic=072312 here]].
--> "Even after studying statistics, all my knowledge and understanding of it goes out the window when I play Fire Emblem and I get mad at math not doing what I think is best for it."
* [[Webcomic/FreeFall Sam Starfall]] uses statistics in artistic fashion to establish that [[http://freefall.purrsia.com/ff500/fv00438.htm riding the top of a moving train is safer than climbing a staircase]].
* ''Webcomic/LarryLeadhead'' applies this sort of reasoning to the wargaming tables.

[[folder:Web Original]]
* Sometimes websites run stories about so-called "winning systems", such as [[http://www.limechew.com/1291# this one]]. The most cursory read of the article reveals that the system this guy has "discovered" is merely the martingale, described further up this page.