
Cohen’s D
 Provides an effect size measure for the independent ttest.
 It indicates the practical importance of a statistically significant t.

Confidence Interval of the Difference
 An interval that estimates the difference between the
 populations means represented by two samples in an independent ttest.

Correlational
 The term used to define a research design in which there are
 no treatment and control groups.
Correlational studies are also called nonexperimental.

Estimated Standard Error of the Mean
 This estimates the standard deviation of the sample means in the distribution of sample means.
 Determined by dividing the sample standard deviation by the square root of the number in the sample, it is a measure of data variability in the ttests.
 This is abbreviated SEm

Experimental
The term used to define a research design in which the subjects are randomly assigned to multiple groups.

Independent Ttest
A test used to determine whether two independent samples are likely drawn from populations with the same mean.

Nonexperimental
 The term used to define a research design in which there are no treatment and control groups.
 Nonexperimental studies are also called correlational.

OmegaSquared
This is an effect size measure for the ttest and for analysis of variance. It indicates how much of the variance in the dependent variable can be explained by manipulating the independent.

One Sample T Test
 A test that determines whether a sample is likely to have been drawn from a specified population.
 Unlike the ztest, it requires no population standard deviation.

One tailed
 A test in which the direction of the significant difference is predicted.
 for example, in ttest, one predicts that the mean of group 1 will be significantly greater, or lesser than the mean of group 2, rather than just significantly different from it.

QuasiExperimental
The term used to define a research design in which there are multiple groups but no random assignment.

Standard Error of the Difference
 The statistic in which the within group's variability is pooled from both samples in an independent ttest.
 It is abbreviated SEd

Before/After TTest
Rather than separate groups that the independentt test test employs, the same group is measured twice, once before the treatment and then after.

Two tailed statistical test
 A test in which the only important factor is whether the test statistic is extreme enough that it is not likely to have occured by chance.
 Whether the test statistic is positive or negative does not matter.

