Values of one variable tend to occur with certain values of another variable; detected when the conditional distributions differ from the marginal distribution ann from each other
Bias
the design of a statistical study is biased if it systematically favors certain outcomes
bivariate data:
Data collected on two variables for each individal in a study
Central Limit Theorem:
When sampling from a non-Normal populaiton, the sampling distribution of x- is approximately Normal whenever the sample is large and random
conditional distribution
the distribution of the vlaues in a single row (or a single column) of a two-way table.