Statistical Methods for Psychology

Degrees of Freedom The degrees of freedom for the matched-sample case are exactly the same as they were for the one-sample case. ...

From Appendix t, we find that. Since is less than 2.262, we will fail to reject and will decide that we have no evidence to sugg ...

Effect Size In Chapter 6 we looked at effect size measures as a way of understanding the magnitude of the effect that we see in ...

had measured the girls’ self-esteem, rather than weight, I would not know what to think if you said that they gained 7.26 self-e ...

samples, it is not the only way. For example, a study of marital relationships might involve asking husbands and wives to rate t ...

Writing up the Results of a Dependent t Suppose that we wish to write up the results of Everitt’s study of family therapy for an ...

variances and. We now draw pairs of samples of size n 1 from population and of size n 2 from population , and record the means a ...

Having found the mean and the variance of a set of differences between means, we know most of what we need to know. The general ...

(Such knowledge is so rare that it is not even worth imagining cases in which we would have it, although a few do exist.) We can ...

Notice that both this formula for t and the one we have just been using involve dividing the difference between the sample means ...

so our conclusions will be the same as theirs.^11 The dependent variable is the degree of arousal at the end of the 4-minute vid ...

Confidence Limits on m 1 – m 2 In addition to testing a null hypothesis about population means (i.e., testing H 0 : m 1 2 m 25 0 ...

For our data on homophobia we have This result expresses the difference between the two groups in standard deviation units, and ...

other scoring low. When presented with sexual explicit homosexual videos, the homophobic group actually showed a higher level of ...

ability” (Aronson, Lustina, Good, Keough, Steele, & Brown, 1998). This feeling of stereo- type threat is then hypothesized t ...

Writing up the Results If you were writing up the results of this experiment, you might write something like the following: This ...

where and are taken to be heterogeneous variances. As noted above, the expression that I have just denoted as is notnecessarily ...

deviation— —where iand jrepresent the ith subject in the jth group. He then proposed running a standard two-sample t test on the ...

A Caution When Welch, Satterthwaite, Behrens, and Fisher developed tests on means that are not de- pendent on homogeneous varian ...

Exercises 217 more aroused. This is what Jones and Tukey call a “reversal,” and the probability of making this error if we use a ...