AP Statistics Summary 2025 EXAM Addition Rule - CORRECT ANSWERSP(A ∪ B) = P(A) + P(A) - P(A ∩ B) aids in computing the chances of one of several events occurring at a given time. Alpha (α) - CORRECT ANSWERSThe probability of a Type I error. See signifi

AP Statistics Summary 2025 EXAM Addition Rule - CORRECT ANSWERSP(A ∪ B) = P(A) + P(A) - P(A ∩ B) aids in computing the chances of one of several events occurring at a given time. Alpha (α) - CORRECT ANSWERSThe probability of a Type I error. See significance level. Alternative Hypothesis - CORRECT ANSWERSThe hypothesis stating what the researcher is seeking evidence of. A statement of inequality. It can be written looking for the difference or change in one direction from the null hypothesis or both. Association - CORRECT ANSWERSRelationship between or among variables. Back-Transform - CORRECT ANSWERSThe process by which values are substituted into a model of transformed data, and then reversing the transforming process to obtain the predicted value or model for nontransformed data. Bar Chart - CORRECT ANSWERSA graphical display used with categorical data, where frequencies for each category are shown in vertical bars. Bell-Shaped - CORRECT ANSWERSOften used to describe the normal distribution. See mound-shaped. Beta (β) - CORRECT ANSWERSThe probability of a Type II error. See power. Bias - CORRECT ANSWERSThe term for systematic deviation from the truth (parameter), caused by systematically favoring some outcomes over others. Biased - CORRECT ANSWERSA sampling method is biased if it tends to produce samples that do not represent the population. Bimodal - CORRECT ANSWERSA distribution with two clear peaks. Binomial Distribution - CORRECT ANSWERSThe probability distribution of a binomial random variable. Binomial Random Variable - CORRECT ANSWERSA random variable x (a) that has a fixed number of trials of a random phenomenon n, (b) that has only two possible outcomes on each trial, (c) for which the probability of a success is constant for each trial, and (d) for which each trial is independent of other trials. Bins - CORRECT ANSWERSThe intervals that define the "bars" of a histrogram. Bivariate Data - CORRECT ANSWERSConsists of two variables, an explanatory and a response variable, usually quantitative. Blinding - CORRECT ANSWERSPractice of denying knowledge to subjects about which treatment is imposed upon them. Blocks - CORRECT ANSWERSSubgroups of the experimental units that are separated by some characteristic before treatments are assigned because they may respond differently to the treatments. Box-And-Whisker Plot/Boxplot - CORRECT ANSWERSA graphical display of the five number summary of a set of data, which also shows outliers. Categorical Variable - CORRECT ANSWERSA variable recorded as labels, names, or other non-numerical outcomes. Census - CORRECT ANSWERSA study that observes, or attempts to observe, every individual in a population. Central Limit Theorem - CORRECT ANSWERSAs the size n of a simple random sample increases, the shape of the sampling distribution of x̄ tends toward being normally distributed. Chance Device - CORRECT ANSWERSA mechanism used to determine random outcomes. Cluster Sample - CORRECT ANSWERSA sample in which a simple random sample of heterogeneous subgroups of a population is selected. Clusters - CORRECT ANSWERSHeterogeneous subgroups of a population. Coefficient of Determination (r²) - CORRECT ANSWERSPercent of variation in the response variable explained by its linear relationship with the explanatory variable. Complement - CORRECT ANSWERSThe compliment of an event is that event not occurring. Complementary Randomized Design - CORRECT ANSWERSOne in which all experimental units are assigned treatments solely by chance. Conditional Distribution - CORRECT ANSWERSSee conditional frequencies. Conditional Frequencies - CORRECT ANSWERSRelative frequencies for each cell in a two-way table relative to one variable. Conditional Probability - CORRECT ANSWERSThe probability of an event occurring given that another has occurred. The probability of A given that B has occurred is denoted as P(A|B). Confidence Intervals - CORRECT ANSWERSGive an estimated range that is likely to contain an unknown population parameter. Confidence Level - CORRECT ANSWERSThe level of certainty that a population parameter exists in the calculated confidence interval. Confounding - CORRECT ANSWERSThe situation where the effects of two or more explanatory variables on the response variable cannot be separated. Confounding Variable - CORRECT ANSWERSA variable whose effect on the response variable cannot be untangled from the effects of the treatment. Contingency Table - CORRECT ANSWERSSee two-way table. Continuous Random Variables - CORRECT ANSWERSThose typically found by measuring, such as heights or temperatures. Control Group - CORRECT ANSWERSA baseline group that may be given no treatment, a faux treatment like a placebo, or an accepted treatment that is to be compared to another. Control - CORRECT ANSWERSThe principle that potential sources of variation due to variables not under consideration must be reduced. Convenience Sample - CORRECT ANSWERSComposed of individuals who are easily accessed or contacted. Correlation Coefficient (r) - CORRECT ANSWERSA measure of the strength of a linear relationship, r=(1/(n-1))Σ((xi-x̄ )/sx)((yi-ȳ)/sy). Critical Value - CORRECT ANSWERSThe value that the test statistic must exceed in order to reject the null hypothesis. When computing a confidence interval, the value of t* (or z*) where ±t* (or ± z*) bounds the central C% of the t (or z) distribution. Cumulative Frequency - CORRECT ANSWERSThe sums of the frequencies of the data values from smallest to largest. Data Set - CORRECT ANSWERSCollection of observations from a sample or population.