STATISTICAL TESTS!

One-Sample t-test

Compare ONE sample mean to a known/hypothesized mean

Two-Sample t-test (Independent Samples)

Compare means between TWO different groups

Paired t-test

Compare before/after or matched pairs on the SAME individuals.

Chi-Square Test (Independence or Goodness-of-Fit)

Analyze CATEGORICAL frequencies, not means.

Correlation

Measure relationship (association) between two numeric variables.

Regression

Predict Y using X, interpret slope + R².

One-Way ANOVA

Compare means across 3+ groups.

“A biologist measures the average weight of 30 frogs to see if it differs from the published average of 12 g.”

Test: One-sample t-test

“Compare average heart rate between frogs exposed to caffeine vs frogs not exposed.”

Test: Two-sample t-test

“Measure the same frogs before and after a diet to see if their weights changed.”

Test: Paired t-test

“Do male and female birds choose perches in different proportions?”
(Data presented as counts: 20 males on perch A, 15 on perch B, etc.)

Test: Chi-square test

“Does wing length correlate with flight speed?”

Test: Correlation

“Does temperature predict metabolic rate?”

Test: Regression

“Compare plant growth among three soil types.”

Test: One-way ANOVA

“Are observed color frequencies of beetles (red: 20, green: 15, brown: 5) consistent with a 1:1:1 expected ratio?”

Test: Chi-square goodness-of-fit

“You collect lizard sprint speeds from four islands and want to see if the island affects speed.”

Test: One-way ANOVA

“Determine whether body length predicts aggression score.”

Test: Regression

One sample mean compared to a known reference value → What test?

One-sample t-test

Two independent groups, comparing averages → What test?

Two-sample t-test

Same subjects measured twice → What test?

Paired t-test

Data are counts / categories, not numeric means → What test?

Chi-square test

Two numeric variables, measuring association only → What test?

Correlation

Predict Y from X; interpret slope and R² → What test?

Regression

Compare means of 3 or more groups → What test?

One-way ANOVA

Testing whether observed counts match expected proportions → What test?

Chi-square goodness-of-fit