AP Statistics Vocabulary
List 2026 | Key Terms,
Definitions & Study Guide
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success|
Updated 2026 Questions and Answers
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Rationales
Included
, Empirical rule States that, in a normal distribution, about 68% of the terms are within one
standard deviation of the mean, about 95% are within two standard deviations,
and about 99.7% are within three standard deviations (normal curve).
Lurking Variable A variable other than x and y that simultaneously affects both variables,
accounting for the correlation between the two.
Null Hypothesis The hypothesis that states there is no difference between two or more sets of
data in a significance test.
Quota Sample A sample deliberately constructed to reflect several of the major characteristics
of a given population.
Probability The likelihood that a particular event will occur.
Descriptive Statistics Statistical procedures used to describe characteristics and responses of groups of
subjects.
Median The middle score in a distribution; half the scores are above it and half are below
it.
Stemplot A graphical representation of a quantitative data set. Leading values of each data
point are presented as stems and second digits are given as leaves.
Data Information gathered from observations.
Margin of Error The range of percentage points in which the sample accurately reflects the
population, the range surrounding a sample's response within which researchers
are confident the larger population's true response would fall.
Normal A sample which follows the Empirical Rule for distribution.
Simple Random Sample Every member of the population has a known and equal chance of selection.
Sampling Distribution The distribution of values taken by the statistic in all possible samples of the same
size from the same population.
Interpolation Using the Least Squares Regression Line to predict a y-value for an x-value within
the x-data set.
Qualitative Data identified by something other than numbers.
Theoretical Probability The ratio of the number of favorable outcomes to the number of possible
outcomes if all outcomes have the same chance of happening.
Block Design The random assignment of subjects to treatments is carried out separately within
each block.
Least Squares Regression Line The line that minimizes the sum of squared residuals.
List 2026 | Key Terms,
Definitions & Study Guide
|Graded A+ | Guaranteed
success|
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
, Empirical rule States that, in a normal distribution, about 68% of the terms are within one
standard deviation of the mean, about 95% are within two standard deviations,
and about 99.7% are within three standard deviations (normal curve).
Lurking Variable A variable other than x and y that simultaneously affects both variables,
accounting for the correlation between the two.
Null Hypothesis The hypothesis that states there is no difference between two or more sets of
data in a significance test.
Quota Sample A sample deliberately constructed to reflect several of the major characteristics
of a given population.
Probability The likelihood that a particular event will occur.
Descriptive Statistics Statistical procedures used to describe characteristics and responses of groups of
subjects.
Median The middle score in a distribution; half the scores are above it and half are below
it.
Stemplot A graphical representation of a quantitative data set. Leading values of each data
point are presented as stems and second digits are given as leaves.
Data Information gathered from observations.
Margin of Error The range of percentage points in which the sample accurately reflects the
population, the range surrounding a sample's response within which researchers
are confident the larger population's true response would fall.
Normal A sample which follows the Empirical Rule for distribution.
Simple Random Sample Every member of the population has a known and equal chance of selection.
Sampling Distribution The distribution of values taken by the statistic in all possible samples of the same
size from the same population.
Interpolation Using the Least Squares Regression Line to predict a y-value for an x-value within
the x-data set.
Qualitative Data identified by something other than numbers.
Theoretical Probability The ratio of the number of favorable outcomes to the number of possible
outcomes if all outcomes have the same chance of happening.
Block Design The random assignment of subjects to treatments is carried out separately within
each block.
Least Squares Regression Line The line that minimizes the sum of squared residuals.
