Statistical Methods for Psychology

358 Chapter 11 Simple Analysis of Variance Exhibit 11.4 JMP analysis of data in Exercise 11.8 Tests that the Variances are Equal ...

11.13 Write an appropriate statistical model for Exercise 11.1. 11.14 Write an appropriate statistical model for Exercise 11.2. ...

360 Chapter 11 Simple Analysis of Variance Induced Mood Negative Positive None 798 5125 16 7 11 13 3 9 13 10 11 24 4 10 20 5 11 ...

this is equal to the average of the variances within each of the nine groups in the experiment. Save this value to use in Chapte ...

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CHAPTER 12 Multiple Comparisons Among Treatment Means CHAPTER 12 Multiple Comparisons Among Treatment Means Objectives To extend ...

A SIGNIFICANTFIN AN ANALYSIS OF VARIANCEis simply an indication that not all the popu- lation means are equal. It does not tell ...

example, we make a comparison by running a t test between two groups and we reject the null hypothesis because our t exceeds , t ...

of the latter are far apart and which are close together. This is a traditional distinction, but one that seems to be less and l ...

will examine group differences regardless of the value of that F. Why, then, do we even need that Fexcept to provide a sense of ...

the animal repeated morphine injections in one setting but then tested it with morphine in a newsetting, the new setting would n ...

Magnitude of Effect We can calculate^2 for these data as SStreat SStotal 5 3497.60 4617.60 5 .76, indicating that treatment diff ...

with from the overall analysis of variance and evaluate the t on degrees of free- dom. When the variances are heterogeneous but ...

Both of these obtained values of t would be evaluated against t.025(35) 5 2.03, and both would lead to rejection of the correspo ...

Sum of Squares for Contrasts One of the advantages of linear contrasts is that they can be converted to sums of squares very eas ...

The Choice of Coefficients In the previous example, it should be reasonably clear why we chose the coefficients we did. They wei ...

never had morphine (Condition S-M) or because they had received morphine in a different context (Mc-M), with the mean of the oth ...

tested using individual t tests. If you take the square root of the Fs for these two contrasts, they will equal 6.72 and 2.47, w ...

At first glance, it would appear that finding sets of coefficients satisfying the require- ment would require that we either und ...

ran. In fact, the contrasts that I ran earlier are not orthogonal to each other, and that does not worry me over much. They addr ...