Effect Size & Power

The Basics

Expressing Your Stats

Probability, Chance, and Error

Terms

100

The measure of the difference between two population means.

What is an effect size?

100

Statistics are to samples as _______ are to populations.

What are parameters?

100

Number of decimal places for reporting r-values and F-ratios.

What is two?

100

Type of sample in which each person in the population has an equal chance to be included.

What is a random sample?

100

The name for the statement that there will be no difference, effect, or change between the groups measured.

What is a null hypothesis?

200

The probability that a study will give a statistically significant result if the research hypothesis is true.

What is statistical power?

200

The most frequent score in a distribution

What is the mode?

200

The type of score which expresses the difference of a score from the mean in units of standard deviation.

What is a z-score?

200

The name for the criterion for significance set by the researcher.

What is the alpha level?

200

The set of all individuals of interest in a particular study.

What is the population?

300

This greater the power, the more likely that you'll get a larger __________.

What is effect size?

300

Type of relationship exemplified by a correlation between final examination grade and course grade.

What is a positive correlation?

300

Cohen's d is an expression of this important measure of magnitude of changes resulting from a treatment.

What is the effect size?

300

The type of error committed when a researcher rejects the null hypothesis when it is, in fact, true.

What is a Type I error?

300

Race, gender and hair color are examples of this type of measurement.

What is nominal or categorical?

400

A procedure of systematically combining and comparing effect sizes of separate studies.

What is a meta-analysis?

400

This is the estimate of the square root of the population variance.

What is the sample standard deviation?

400

A graph of ordinal or ratio data in which adjacent, touching, vertical bars express the frequency for that category.

What is a histogram?

400

The alpha level value when there is no more than a one in twenty chance of significant results being due to chance (sampling error).

What is .05?

400

For a sample of n scores, n-1.

What are degrees of freedom?

500

This is your conclusion when results are not statistically significant and your sample sizes are small.

What is inconclusive?

500

In a normal distribution, 68.26% of the cases.

What falls within +- one standard deviation of the mean?

500

The category of effect size associated with an r value of .78

What is a large effect?

500

The average distance between the sample mean and the population mean.

What is the standard error?

500

Based on sample size and other factors, this is the statistic's ability to correctly reject the null hypothesis.

What is statistical power?