Stat 371 Hypothesis Testing: Two-Sample Tests

Flashcards covering key vocabulary and concepts from the lecture on hypothesis testing and two-sample tests.

Two-Sample Tests

Statistical methods used to determine if there is a significant difference between the means or proportions of two groups.

Independent Groups

Two groups are independent when the observations in one have no natural pairing with observations in the other.

Two-Sided Hypothesis Test

A test where the alternative hypothesis states that there is a difference (greater than or less than), but does not specify the direction.

One-Sided Hypothesis Test

A test where the alternative hypothesis states that one parameter is either greater than or less than another parameter.

t-test

A statistical test used to compare the means of two groups, calculated by comparing the difference between sample means to the variation within the samples.

Welch’s t-test

A version of the t-test that does not assume equal variances between the two groups.

Pooled t-test

A t-test that assumes equal variances in the two groups being compared.

Null Hypothesis (H0)

A statement that indicates no effect or no difference, used as a default hypothesis that researchers aim to reject.

Alternative Hypothesis (HA)

The hypothesis that there is an effect or a difference, which researchers test against the null hypothesis.

Two-Sample Proportion Test

A statistical test used to compare the proportions of a binary outcome between two groups.

Wilcoxon Rank-Sum Test

A non-parametric test used to compare two independent groups when data are skewed or not normally distributed.

Paired Data

Data where each observation in one group is directly matched with an observation in the other group, useful for comparing conditions.

Paired T-Test

A statistical test used to compare the means of two related groups.

Sign Test for Paired Data

A non-parametric test that assesses whether the median of the differences between paired observations is zero.

Wilcoxon Signed-Rank Test

A non-parametric test used to compare the distributions of two paired groups.

Degrees of Freedom (df)

A value used in statistical tests that reflects the number of independent values in a calculation.

Confidence Interval (CI)

A range of values that is likely to contain the true parameter with a specified level of confidence.

p-value

The probability of obtaining a result at least as extreme as the one that was actually observed, under the assumption that the null hypothesis is true.

Central Limit Theorem (CLT)

A statistical theory that states that, given a sufficiently large sample size, the distribution of the sample means will approach a normal distribution.