{
 "source": "https://peabody.kids/flashcards/tp-ap-statistics",
 "id": "tp-ap-statistics",
 "title": "AP Statistics Key Terms",
 "category": "test-prep",
 "subject": "AP Statistics",
 "levels": [
  "9-12",
  "college"
 ],
 "description": "Data description, study design, probability and inference vocabulary.",
 "tags": [
  "ap",
  "statistics"
 ],
 "frontLabel": "Term",
 "backLabel": "Meaning",
 "cards": [
  [
   "Population",
   "The entire group being studied"
  ],
  [
   "Sample",
   "The part of the population actually measured"
  ],
  [
   "Parameter",
   "A number describing a population"
  ],
  [
   "Statistic",
   "A number describing a sample"
  ],
  [
   "Categorical variable",
   "Places individuals into groups"
  ],
  [
   "Quantitative variable",
   "Takes numerical values that can be measured or counted"
  ],
  [
   "Discrete variable",
   "Takes countable values"
  ],
  [
   "Continuous variable",
   "Takes any value in an interval"
  ],
  [
   "Bar graph",
   "Shows counts or percentages for categories"
  ],
  [
   "Histogram",
   "Bars showing how quantitative data are distributed"
  ],
  [
   "Dotplot",
   "Each value shown as a dot above a number line"
  ],
  [
   "Boxplot",
   "Display of the five-number summary"
  ],
  [
   "Five-number summary",
   "Minimum, Q1, median, Q3, maximum"
  ],
  [
   "Interquartile range",
   "Q3 minus Q1"
  ],
  [
   "Outlier rule",
   "Values beyond 1.5 times IQR from the quartiles"
  ],
  [
   "Mean",
   "Sum of values divided by their number"
  ],
  [
   "Median",
   "Middle value when ordered"
  ],
  [
   "Resistant measure",
   "A statistic not strongly affected by outliers, like the median"
  ],
  [
   "Standard deviation",
   "Typical distance of values from the mean"
  ],
  [
   "Variance",
   "The square of the standard deviation"
  ],
  [
   "Skewed right",
   "Long tail toward larger values; mean greater than median"
  ],
  [
   "Symmetric distribution",
   "Both sides are mirror images"
  ],
  [
   "Z-score",
   "How many standard deviations a value is from the mean"
  ],
  [
   "Normal distribution",
   "Bell-shaped, symmetric distribution"
  ],
  [
   "Empirical rule",
   "About 68, 95 and 99.7 percent within 1, 2 and 3 standard deviations"
  ],
  [
   "Percentile",
   "Percent of values at or below a given value"
  ],
  [
   "Scatterplot",
   "Graph of two quantitative variables"
  ],
  [
   "Correlation r",
   "Measures strength and direction of a linear relationship, -1 to 1"
  ],
  [
   "Least-squares regression line",
   "Line minimizing the sum of squared residuals"
  ],
  [
   "Residual",
   "Actual value minus predicted value"
  ],
  [
   "Residual plot",
   "Graph used to check if a linear model fits"
  ],
  [
   "Coefficient of determination",
   "r squared, share of variation explained by the model"
  ],
  [
   "Slope",
   "Predicted change in y for each one-unit increase in x"
  ],
  [
   "Extrapolation",
   "Predicting outside the range of the data, which is risky"
  ],
  [
   "Influential point",
   "A point that greatly changes the regression line"
  ],
  [
   "Lurking variable",
   "An unmeasured variable influencing the relationship"
  ],
  [
   "Confounding",
   "Effects of variables cannot be separated"
  ],
  [
   "Simple random sample",
   "Every group of the chosen size is equally likely"
  ],
  [
   "Stratified random sample",
   "Random samples from each subgroup"
  ],
  [
   "Cluster sample",
   "Randomly choose groups and survey everyone in them"
  ],
  [
   "Systematic sample",
   "Choose every kth individual"
  ],
  [
   "Convenience sample",
   "Easy-to-reach individuals; likely biased"
  ],
  [
   "Voluntary response bias",
   "Bias from people choosing to respond"
  ],
  [
   "Undercoverage",
   "Some groups are left out of the sampling frame"
  ],
  [
   "Nonresponse bias",
   "Selected individuals do not respond"
  ],
  [
   "Response bias",
   "Answers distorted by question wording or situation"
  ],
  [
   "Observational study",
   "Observes without assigning treatments"
  ],
  [
   "Experiment",
   "Researchers impose treatments on subjects"
  ],
  [
   "Randomized block design",
   "Group similar subjects into blocks, then randomize within blocks"
  ],
  [
   "Matched pairs design",
   "Subjects paired or each used twice to compare treatments"
  ],
  [
   "Replication",
   "Using enough subjects so results are reliable"
  ],
  [
   "Blinding",
   "Hiding treatment information to reduce bias"
  ],
  [
   "Law of large numbers",
   "Relative frequency approaches probability with more trials"
  ],
  [
   "Sample space",
   "All possible outcomes"
  ],
  [
   "Complement rule",
   "P(not A) = 1 - P(A)"
  ],
  [
   "Addition rule",
   "P(A or B) = P(A) + P(B) - P(A and B)"
  ],
  [
   "Independent events",
   "One does not change the probability of the other"
  ],
  [
   "Conditional probability",
   "P(A | B) = P(A and B) / P(B)"
  ],
  [
   "Mutually exclusive",
   "Events that cannot occur together"
  ],
  [
   "Random variable",
   "A numerical outcome of a random process"
  ],
  [
   "Expected value",
   "The long-run average of a random variable"
  ],
  [
   "Binomial setting",
   "Fixed trials, two outcomes, independent, constant probability"
  ],
  [
   "Binomial mean",
   "np"
  ],
  [
   "Binomial standard deviation",
   "sqrt(np(1 - p))"
  ],
  [
   "Geometric distribution",
   "Counts trials until the first success"
  ],
  [
   "Sampling distribution",
   "Distribution of a statistic across all samples of a given size"
  ],
  [
   "Unbiased estimator",
   "A statistic whose mean equals the parameter"
  ],
  [
   "Central limit theorem",
   "Sample means become approximately normal as sample size grows"
  ],
  [
   "Standard error",
   "Estimated standard deviation of a statistic"
  ],
  [
   "Margin of error",
   "Critical value times the standard error"
  ],
  [
   "Confidence interval",
   "A range of plausible values for a parameter"
  ],
  [
   "Confidence level",
   "Long-run percent of intervals that capture the parameter"
  ],
  [
   "Null hypothesis",
   "The claim of no effect or no difference"
  ],
  [
   "Alternative hypothesis",
   "The claim tested for evidence"
  ],
  [
   "P-value",
   "Probability of results at least as extreme as observed if the null is true"
  ],
  [
   "Significance level",
   "Cutoff probability for rejecting the null, often 0.05"
  ],
  [
   "Type I error",
   "Rejecting a true null hypothesis"
  ],
  [
   "Type II error",
   "Failing to reject a false null hypothesis"
  ],
  [
   "Power",
   "Probability of correctly rejecting a false null"
  ],
  [
   "One-sample z-test for proportion",
   "Tests a claim about a population proportion"
  ],
  [
   "t-distribution",
   "Used with sample standard deviation for means; heavier tails than normal"
  ],
  [
   "Degrees of freedom",
   "Number of independent pieces of information"
  ],
  [
   "Two-sample t-test",
   "Compares means of two independent groups"
  ],
  [
   "Paired t-test",
   "Compares means within matched pairs"
  ],
  [
   "Chi-square goodness of fit",
   "Tests whether counts match a claimed distribution"
  ],
  [
   "Chi-square test of independence",
   "Tests association between two categorical variables"
  ],
  [
   "Expected count",
   "Count predicted if the null is true"
  ],
  [
   "Inference for slope",
   "t-test of the slope of a regression line"
  ],
  [
   "Conditions for inference",
   "Random, independent (10 percent rule), and normal or large sample"
  ],
  [
   "10 percent condition",
   "Sample should be under 10 percent of population for independence"
  ],
  [
   "Large counts condition",
   "np and n(1-p) each at least 10"
  ],
  [
   "Statistical significance",
   "Results unlikely to be due to chance alone"
  ],
  [
   "Causation conclusion",
   "Only well-designed randomized experiments support causal claims"
  ]
 ]
}