PSYC_2016_FINAL_STUDY_GUIDE_

What is a frequency distribution?

A summary of how often scores or categories occur in a dataset.

What is the formula to find the Real Range in a frequency distribution?

Real Range = (Max Value - Min Value) + 1.

How do you calculate the Interval Width for a frequency distribution?

Interval Width = Real Range / Number of Intervals.

What is cumulative frequency?

A running total of frequencies.

What is relative frequency?

Frequency / Total Count, useful for comparing datasets.

What is the mean?

The average of a dataset; calculated as X̄ = ∑X / N.

What is the median and how is it determined?

The middle value of ordered data; for odd N, it’s the middle value; for even, it’s the average of the two middle values.

What is variance and how is it calculated for a population?

Variance (population) = σ² = ∑(X - μ)² / N.

What is the formula for the standard deviation?

Standard Deviation (SD) = √Variance.

What characterizes a normal distribution?

It is symmetrical and bell-shaped, defined by the mean and standard deviation.

What does the 68–95–99.7 rule state?

68% of data lies within 1 SD of the mean, 95% within 2 SDs, and 99.7% within 3 SDs.

What is a z-score?

A standard score indicating how many standard deviations a value is from the mean.

What is the Central Limit Theorem?

The sampling distribution of the mean approaches normality as sample size increases (n > 30).

What is the purpose of hypothesis testing?

To determine if a sample mean differs from a known population mean.

What is the formula for a one-sample t-test?

t = (M - μ) / SE, where SE is the standard error.

What is Pearson's r?

A measure of the strength and direction of a linear relationship between two variables.

What does a linear regression predict?

It predicts the value of one variable (Y) based on another (X).

What is the formula for a t-test comparing independent groups?

t = (M1 - M2) / sqrt(s12/n1 + s22/n2).

What is ANOVA used for?

It compares means across three or more groups.

When is it appropriate to use a related samples t-test?

To compare means from related groups, such as pre-test vs post-test measurements.