Statistical Methods for Psychology

faces. (The means were 3.26 and 2.64, respectively.) But notice also that the ratings for the composites of 32 faces are conside ...

upper 25% and the lower 25% of the distribution and taking the range of what remains. The point that cuts off the lowest 25% of ...

The Average Deviation At first glance it would seem that if we want to measure how scores are dispersed around the mean (i.e., d ...

Set 4(X) Set 32(Y) From these calculations we see that the difference in variances reflects the differences we see in the distri ...

deviations of each score from the mean. Granted, these deviations have been squared, summed, and so on, but at heart they are st ...

Similarly, for the sample standard deviation Recently people whose opinions I respect have suggested that I should remove such f ...

that large deviations are disproportionately represented. You might keep this in mind the next time you use a measuring instrume ...

like taking a multiple-choice test on Mongolian history without having taken the course. The data follow: Read Did Not Read Pass ...

Unbiasedness Suppose we have a population for which we somehow know the mean (μ), say, the heights of all basketball players in ...

these outliers, whereas the mean does not. This property is called the resistanceof the estimator. In recent years, considerably ...

for purposes of estimating variability. Thus, you lose that degree of freedom that we dis- cussed, and you have only N 21 dfleft ...

We earlier defined the median location of a set of Nscores as (N 1 1)/2. When the median location is a whole number, as it will ...

Inner fences and adjacent values can cause some confusion. Think of a herd of cows scattered around a field. (I spent most of my ...

outliers. However, boxplots are normally used as informal heuristic devices, and subtle dif- ferences in definition are rarely, ...

Report: RxTime NStim N Mean Median Std. Deviation Variance 1 100 53.27 50.00 13.356 178.381 3 100 60.65 60.00 9.408 88.513 5 100 ...

fall within a set called linear transformations,in which we multiply each Xby some constant (possibly 1) and add a constant (pos ...

or disagree with each of several items. To prevent the subjects from simply checking the same point on the scale all the way dow ...

Key Terms 55 Exercise 3.42.) Later in this book you will see how to use other nonlinear transformations (e.g., square root or lo ...

56 Chapter 2 Describing and Exploring Data Exercises Many of the following exercises can be solved using either computer softwar ...

Exercises 57 2.9 In Exercise 2.8, what would be the first and third quartiles for males and females? 2.10 The following stem-and ...