Chapter 9 PSY 110 -- Spring 2022

t-Test

A statistical test that compares the means of two groups to determine if they are significantly different from each other.

t Statistic

A value calculated from a t-test that indicates how many standard deviations a sample mean is from the population mean under the null hypothesis.

Degrees of Freedom (df)

The number of independent values in a calculation; for a single sample t-test, df is calculated as n - 1.

Independent Observations

Assumption that the samples tested in a t-test are independent of each other.

Normality

Condition that the population sampled must approximate a normal distribution.

Estimated Standard Error (sM)

An estimate of the standard error (σM) when the population standard deviation (σ) is unknown.

Significance Level (α)

The threshold for determining whether a result is statistically significant, commonly set at 0.05.

Critical Region

The area in the tails of the distribution where the null hypothesis is rejected.

Effect Size

A measure of the strength of the relationship between two variables or the size of a treatment effect.

Cohen's d

A measure used to indicate the standardized difference between two means.