Statistical Methods for Psychology

8.6 Power Calculations in More Complex Designs In this chapter I have constrained the discussion largely to statistical procedur ...

8.8 Retrospective Power In general the discussion above has focused on a priori power,which is the power that we would calculate ...

One reason why we might calculate retrospective power is to help in the design of future research. Suppose that we have just com ...

Exercises 241 there is a 1:1 relationship between pand retrospective power. One can be derived from the other. Thus retrospectiv ...

242 Chapter 8 Power 8.4 A second investigator thinks that she can show that a quite different manipulation can raise the mean in ...

Exercises 243 been classed as delinquent in the past. Or, he has access to 25 high-school dropouts who have a history of delinqu ...

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CHAPTER 9 Correlation and Regression CHAPTER 9 Correlation and Regression Objectives To introduce the concepts of correlation an ...

INCHAPTER 7 WE DEALT WITH TESTING HYPOTHESESconcerning differences between sample means. In this chapter we will begin examining ...

other (regression) and of obtaining a measure of the degree of this relationship (correla- tion). The only restriction we will i ...

In a scatterplot, the predictorvariable is traditionally represented on the abscissa, or X-axis, and the criterionvariable on th ...

countries with the longest life expectancy (Iceland and Japan) spend nearly the same amount of money on health care as the count ...

250 Chapter 9 Correlation and Regression 4.2 –2 –1 0 Theoretical quantiles Loge symptoms 12 4.4 4.6 4.8 5.0 Sample quantiles Tab ...

To define the covariance mathematically, we can write From this equation it is apparent that the covariance is similar in form t ...

For computational purposes, a simple expression for the covariance is given by For the full data set represented in abbreviated ...

(23, 18) and (40, 66). (I pulled those numbers out of the air.) If you plot these points and fit a line to them, the line will f ...

As you may remember from high school, the equation of a straight line is an equation of the form Y 5 bX 1 a. For our purposes, w ...

earlier editions of this book or in Draper and Smith (1981, p. 13). The solution to the problem yields what are often called the ...

Interpretations of Regression In certain situations the regression line is useful in its own right. For example, a college admis ...

Standardized Regression Coefficients Although we rarely work with standardized data (data that have been transformed so as to ha ...