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🎲AP Statistics Unit 4 Vocabulary

78 essential vocabulary terms and definitions for Unit 4 – Probability, Random Variables, and Probability Distributions

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🎲Unit 4 – Probability, Random Variables, and Probability Distributions
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🎲Unit 4 – Probability, Random Variables, and Probability Distributions

4.10 Introduction to the Binomial Distribution

TermDefinition
binomial distributionA probability distribution that describes the number of successes in a fixed number of independent trials, each with the same probability of success.
binomial probability functionThe formula P(X=x)=C(n,x)p^x(1-p)^(n-x) that calculates the probability of exactly x successes in n independent trials with probability of success p.
binomial random variableA random variable that counts the number of successes in a fixed number of repeated independent trials, where each trial has two possible outcomes.
independent trialsRepeated experiments or observations where the outcome of one trial does not affect the outcome of any other trial.
number of failuresThe count of unfavorable outcomes in a sample, denoted as n(1-p̂), used to verify the normality condition.
number of successesThe count of favorable outcomes in a sample, denoted as np̂, used to verify the normality condition.
probability distributionA function that describes the likelihood of all possible values of a random variable.
probability of successThe constant probability p that an individual trial results in a success in a binomial experiment.
random number generatorA tool or method used to randomly select items from a population for inclusion in a simple random sample.
simulationA method of modeling random events so that simulated outcomes closely match real-world outcomes, used to estimate probabilities.

4.1 Introducing Statistics

TermDefinition
patterns in dataObservable regularities or trends that appear in a dataset, which may or may not indicate non-random behavior.
variationDifferences in data that occur by chance due to the random nature of sampling, rather than from systematic causes.

4.11 Parameters for a Binomial Distribution

TermDefinition
binomial distributionA probability distribution that describes the number of successes in a fixed number of independent trials, each with the same probability of success.
meanThe average value of a dataset, represented by μ in the context of a population.
parameterA numerical summary that describes a characteristic of an entire population.
probabilityThe likelihood or chance that a particular outcome or event will occur, expressed as a value between 0 and 1.
random variableA variable whose value is determined by the outcome of a random phenomenon and can take on different numerical values with associated probabilities.
standard deviationA measure of how spread out data values are from the mean, represented by σ in the context of a population.

4.12 The Geometric Distribution

TermDefinition
geometric distributionA probability distribution that models the number of trials needed to achieve the first success in a sequence of independent Bernoulli trials, each with the same probability of success.
geometric probability functionThe formula P(X=x)=(1-p)^(x-1)p that calculates the probability that the first success occurs on trial x.
geometric random variableA random variable that represents the number of the trial on which the first success occurs in a sequence of independent trials.
independent trialsRepeated experiments or observations where the outcome of one trial does not affect the outcome of any other trial.
meanThe average value of a dataset, represented by μ in the context of a population.
number of failuresThe count of unfavorable outcomes in a sample, denoted as n(1-p̂), used to verify the normality condition.
number of successesThe count of favorable outcomes in a sample, denoted as np̂, used to verify the normality condition.
parameterA numerical summary that describes a characteristic of an entire population.
probabilityThe likelihood or chance that a particular outcome or event will occur, expressed as a value between 0 and 1.
probability of successThe constant probability p that an individual trial results in a success in a binomial experiment.
random variableA variable whose value is determined by the outcome of a random phenomenon and can take on different numerical values with associated probabilities.
standard deviationA measure of how spread out data values are from the mean, represented by σ in the context of a population.

4.2 Estimating Probabilities Using Simulation

TermDefinition
eventA collection of one or more outcomes from a random process.
law of large numbersThe principle that simulated or empirical probabilities tend to get closer to the true probability as the number of trials increases.
outcomeThe result of a single trial of a random process.
random processA process that generates results determined by chance, where the outcome cannot be predicted with certainty in advance.
relative frequencyThe proportion of observations in a category, expressed as a decimal, fraction, or percentage of the total.
simulationA method of modeling random events so that simulated outcomes closely match real-world outcomes, used to estimate probabilities.

4.3 Introduction to Probability

TermDefinition
complement of an eventThe set of all outcomes in the sample space that are not in event E, denoted E' or E^C, representing 'not E'.
equally likelyA condition where all outcomes in a sample space have the same probability of occurring.
eventA collection of one or more outcomes from a random process.
long runA large number of repetitions of a probability experiment where the relative frequency of an event approaches its true probability.
outcomeThe result of a single trial of a random process.
probabilityThe likelihood or chance that a particular outcome or event will occur, expressed as a value between 0 and 1.
random processA process that generates results determined by chance, where the outcome cannot be predicted with certainty in advance.
relative frequencyThe proportion of observations in a category, expressed as a decimal, fraction, or percentage of the total.
sample spaceThe set of all possible non-overlapping outcomes of a random process.

4.4 Mutually Exclusive Events

TermDefinition
intersectionThe set of outcomes that belong to both event A and event B, denoted A ∩ B.
joint probabilityThe probability that two events A and B both occur, denoted P(A ∩ B).
mutually exclusiveTwo events that cannot occur at the same time; events with no outcomes in common.

4.5 Conditional Probability

TermDefinition
conditional probabilityThe probability that one event will occur given that another event has already occurred, denoted P(A | B).
joint probabilityThe probability that two events A and B both occur, denoted P(A ∩ B).
multiplication ruleA probability rule stating that P(A ∩ B) = P(A) · P(B | A), used to find the probability that two events both occur.

4.6 Independent Events and Unions of Events

TermDefinition
addition ruleA probability rule stating that P(A ∪ B) = P(A) + P(B) - P(A ∩ B), used to find the probability of the union of two events.
conditional probabilityThe probability that one event will occur given that another event has already occurred, denoted P(A | B).
independent eventsEvents A and B are independent if knowing whether event A has occurred does not change the probability that event B will occur.
intersectionThe set of outcomes that belong to both event A and event B, denoted A ∩ B.
union of eventsThe event that either event A or event B or both will occur, denoted P(A ∪ B).

4.7 Introduction to Random Variables and Probability Distributions

TermDefinition
centerA measure indicating the middle or typical value of a distribution.
cumulative probability distributionA representation (as a table or function) showing the probability that a random variable is less than or equal to each of its possible values.
discrete random variableA random variable that takes on a countable number of distinct values, often representing counts or categorical outcomes.
populationThe entire group of individuals or items from which a sample is drawn and about which conclusions are to be made.
probability distributionA function that describes the likelihood of all possible values of a random variable.
random processA process that generates results determined by chance, where the outcome cannot be predicted with certainty in advance.
random variableA variable whose value is determined by the outcome of a random phenomenon and can take on different numerical values with associated probabilities.
shapeThe overall form or pattern of a distribution, including characteristics like skewness and modality.
spreadA measure of how dispersed or variable the outcomes of a probability distribution are, such as range, variance, or standard deviation.

4.8 Mean and Standard Deviation of Random Variables

TermDefinition
discrete random variableA random variable that takes on a countable number of distinct values, often representing counts or categorical outcomes.
expected valueThe long-run average outcome of a random variable, equivalent to the mean of a discrete random variable.
meanThe average value of a dataset, represented by μ in the context of a population.
parameterA numerical summary that describes a characteristic of an entire population.
standard deviationA measure of how spread out data values are from the mean, represented by σ in the context of a population.

4.9 Combining Random Variables

TermDefinition
independent random variablesRandom variables where knowing the value or probability distribution of one does not change the probability distribution of the other.
linear combinationsExpressions of the form aX + bY where X and Y are random variables and a and b are real number coefficients.
linear transformationsChanges to a random variable of the form Y = a + bX, where a and b are constants that shift and scale the distribution.
meanThe average value of a dataset, represented by μ in the context of a population.
probability distributionA function that describes the likelihood of all possible values of a random variable.
random variableA variable whose value is determined by the outcome of a random phenomenon and can take on different numerical values with associated probabilities.
standard deviationA measure of how spread out data values are from the mean, represented by σ in the context of a population.
varianceA measure of the spread or dispersion of a probability distribution, denoted as σ², indicating how far values typically deviate from the mean.