Drop rate

Drop rate is a common but unofficial term used by players to denote the expected average amount (frequency) of an item in relation to all items granted by a random game process in the long run, usually expressed in percent. Examples for random game processes in Asphalt 8: Airborne are opening random containers like Pro Kit Boxes, but also daily ad rewards. Mathematically,
: a drop rate is the expected value of an item's average relative frequency.
The games themselves did not use the term "drop rate" at first. For example, when an Asphalt 8 player taps on the icon of a Pro Kit Box, the displayed screen only shows percentages without further information on their meaning. This often leads to misunderstandings as players can be tempted to understand the values as probabilities or even guarantees, thinking that a percentage of for a desired card in a 4-item box should grant 1 card in every box. This is not the case.
Asphalt Xtreme introduced the term "drop chance" with a modified meaning, and finally, Asphalt 9: Legends took over the term "drop rate" and displayed it in-game.
Drop rates change frequently. While they are usually stable between two game updates, they will almost surely change when a new update comes out. Random containers on have a "last checked" tag that indicates when the official box data, including drop rates, was checked. Example:
== Asphalt 8: Airborne ==
=== Drop rate and guarantee ===
Drop rates do not guarantee the same ratio for every single box. As drop rates are average expected values, they are only achieved in the long run, when a large number of boxes is opened (see law of large numbers). Values for a single box can differ significantly.
This is also the reason why WikiProject Statistics has set the "acceptable" sample size for a box to a minimum of 200 cards. Experience has shown that this sample size allows making first predictions and reduces the risk of false conclusions to an acceptable level.
:A drop rate is not a guarantee for a single box. It is a long-term average that predicts the outcome of experiments in the long run with a big sample size.
==== Boxes with guaranteed items ====
Although a drop rate is not a guarantee in itself, it can be more important than guarantees provided in the box description. The , for example, officially grants 1 guaranteed V8 Engine, while Engine Boxes don't have this guarantee.
* Players who need only 1 V8 Engine will open the Champion Kit Box first because they can be sure to get the desired engine.
* However, if many V8 Engines are needed, it is recommended to open Engine Boxes first, because in the long run, their drop rate of V8 Engines is higher than that of Champion Kit Boxes.
Note: The game does not provide drop rates for single cards. The values in the table to the right are unofficial results of statistical analyses by WikiProject Statistics.
:In the long run, drop rates are more important than guarantees.
==== Fixed drop rates ====
An exception to the above-mentioned rules are dedicated Championship, R&D and EDD boxes. Their drop rates are fixed, they guarantee the relative frequencies for every particular box.
Example: The (Type 1) of the Lotus Evora Sport 410 R&D grants 10 cards and has the drop rates . As the only rare card the car needs is Mid-Tech, players can be sure to get 1 Mid-Tech card from every box ( of 10 cards).
Unfortunately, the 2019 Spring Update has changed this rule for most new Championship and R&D Boxes:
* The amount of Tech cards in these boxes is now random (so corresponding drop rates show average relative frequencies), while
* Engine and Part cards remain fixed (with guaranteed relative frequencies for every particular box).
Affected boxes are those of the Rezvani Beast X, Pininfarina H2 Speed, McLaren 600LT and probably of all future special events.
=== Drop rate and probability ===
The probability of getting a desired card can often be inferred from its drop rate. In many (but not all) cases, drop rate and probability are equal.
The reason for this difference is that the drop rate predicts the result for many repetitions of an experiment ( opening a large number of boxes), whereas the probability predicts the result of one repetition (opening a single box).
==== Random experiments ====
An experiment is random if there are no guarantees for certain events. In this case, the drop rate of an event equals the probability that it will occur. 
The , for example, does not guarantee any cards, so its content is completely random. Its official drop rate of cards is . This means that in the long run, the amount of legendary cards a player obtains from this box will converge to of all obtained cards. If 10,000 boxes are opened, the number of legendary cards among them will likely be , so picking a random card from these 10,000 cards will deliver a legendary card with a probability of . This is the same result as if the player opened only one box.
: The drop rate of an item equals the probability of obtaining it when the outcome of the experiment is completely random.
==== Experiments with guarantees ====
Many boxes in Asphalt 8 have official or undocumented guarantees.
The , for example, has the official guarantee that at least 1 of its 4 cards will be . Its official drop rate of rare cards is , but the probability of getting a rare card from one box is (because it's guaranteed).
: Drop rate and probability are not the same if an experiment includes guaranteed events.
Nevertheless, it is possible to deduce further probabilities from experiments with guarantees if the guaranteed events are excluded: Taking out the guaranteed rare card from the content of an Extra Box makes the experiment completely random again, creating a 3-card box with no guarantees.
* The guaranteed card makes up of all cards. Taking it out will leave the remaining cards. of these will be rare. , so the probability of getting an additional rare card is .
* The drop rate of cards out of 4 delivers out of 3, so the real probability of obtaining a common card from an Extra Box is .
* Analogously, the probability of getting a card from an Extra Box (drop rate ) is .
== Asphalt Xtreme ==
As Boxes in Asphalt Xtreme have a different system of granting cards, the game has introduced the term "drop chance". In the other games, "drop" normally means that one card is dropped; in Asphalt Xtreme it means that a random amount of this card is dropped. Mathematically, a drop consists of two nested, but different random processes: The first determines the card type, the second determines the number of cards.
All drop chances are drop rates because the term denotes the expected value of a drop's average relative frequency.
If a box in Asphalt Extreme does not grant guaranteed cards, the drop chance of a card and the probability of getting it are equal.
== See also ==
* Box info
* Expected value
* Law of large numbers
* Frequency
* Probability
Category:Gameplay elements
Category:Drop rates