Errata for the 8th edition

for Statistical Methods for Psychology

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From past experience I know that there will be errors. I will add them in as I, or others, find them, along with recognition of the person who reported them. I have had many good corrections from John Woodard, at Wayne State, Dale Berger, at Clarement graduate School, and Jodi Goodman, at West Virginia University. I have not always thanked them for each individual contribution, but I really appreciate their attention.

The Text

Page Line Correction
Throughout Decision Tree I keep referring to the "decision tree" at the front of the book, but it isn't there. You can get a copy (not a very good one) at this link. I want to thank Elizabeth Parco for pointing this out.
31 Table 2.4 Andrea Eves at Edith Cowan University in Australia noted that the 5th equation should read sigma(X-Y), not sigma(XY).
44 1st line Elena Harman at Claremont Graduate University pointed out the the equation should read "(10-5)2 = 25."
56 Exercise 2.5 The reference to Figure 2.5 should be to Figure 2.9. Credit for finding this should go to Jacqueline Lucas of Hawaii Pacific University.
57 Exercise 2.15 The reference to Exercise 2.17 should be to Exercise 2.14. This was pointed out by Charles Van Liew at SDSU.
64 Last full paragraph Park Hyeon noticed that when I say "6% of cases were among clients of commercial sex workers...", the true value is 7%.
67 First Partial paragraph Jodi Goodman, of West Verginia University, pointed out that density is discussed in Chapter 5
75 Last partial paragraph Michael Erickson at Hawaii Pacific University pointed out that I reversed the axes. The expected quantiles would go on the X axis. It doesn't really matter in the abstract, but I wrote them out the other way in Figure 3.10. You have to be consistent, and I wasn't.
76 First paragraph Andrew Waters at the Uniformed Services University pointed out that I corrected Figure 3/10 from the previous edition, but that the text describing the relationship between expected and obtained quantiles is still reversed. The numerical values of -1, -2, 2, and 3 should be -2, -1, 3, and 2.
115 Section 5.5 The reference to Chapter 6 should be to Chapter 3.
145 First equation The denominatior should be 825. Jackie Schroeder at Cal State San Marcos found this error.
148 End 2nd full paragraph Elena Harman noted that I have my examples confused. When I said "just as it was for the standard chi-square test," I should have said "for the data in Table 6.4."
155 Second paragraph The bold entries refered to are the main daigonal in the table.
163 5th line from bottom Jodi Goodman pointed out that the risk ratios should be 1.40, 2.13, 4.20.
172 Exercise 6.22 The reference should be to Exercise 6.8.
173 Ex6.28 This example is correct, but the solutions manual reversed "presence" and "Absence" for rater B.
182 Near bottom The reference to Figure 12.3 should be Figure 7.2. I think that I am getting my books mixed up.
184 Last word The word should be "smaller," not "larger."
191 Third line from bottom H0 should be H1.
192 Middle "m" should be μ
195 First equation I can't multiply correctly. Brian Stephens pointed out that the result should be 66.4, not 64.4. It is there twice.
199 Figure captiontd> Thge relationship is between "Before Therapy" and "Weight Gain."
208 Figure 7.8 There is some bad typesetting here. If you put a carriage return just before the row that starts with "mean", it is easier to see that the first mean is μ1. The line with = X̄1∞ etc. is separate.
219 13 lines from bottom. Take out "not" so as to read "If the variances are homogeneous you pool the variance estimates, ..." Thanks again to Michael Erickson.
234 10th line from bottom The word "interesting" should be "interested." Thanks to Matt Semmel at UNLV.
235 Last line "d" should be "delta." Thanks to Mark Yates at the University of South Alabama."
245 Two lines below Figure 8.6 "d" is the "effect size." Thanks to Michael Erickson Yates at the Hawaii Pacific University.
256 Table 9-1 The file in the dataset named "Tab9-1.sav" was the wrong file. I have since corrected that.
267 Last line before last equation that should read "Ŷ" instead of" Ȳ" Thanks to Jodi Goodman at the West Virginia University.
274 2nd line from bottom This should say "conditional on a fixed value of X."
276 Middle page John Woodard at Wayne State pointed out that I wrote s'Y.X when I meant to write s''Y.X. The numerical part of that set of equations is correct. Nic Barreta at Claremont Graduate University found the same error.
281 Last line before last equation That correlation is really r = .529. Thanks to Jodi Goodman at the West Virginia University.
283 Last three equations My terminology is sloppy here. I am solving for the pooled variance estimate, so I should have used sp2 instead of writing sY.X2.
292 Fig9.11 The dashed line with the steeper slope should be dotted. Thanks to Dale Berger at Claremont Graduate University.
293 Section 9.16 Dale Berger pointed out that in those equations the values for ρ1 should be ρ′1--i.e. use Fisher's transformation. This will change the computed results slightly. I feel bad when I make a careless mistake, but I feel much worse when I make a stupid one. Using G*Power to solve this would leave the correct answer of N = 82
297 Ex9.22 The printout here is wrong. John Woodard at Wayne State pointed out that it is based on only 48 states. I have no idea why that happened. It does not alter the answer to the question, but it is certainly a foolish error.
327 Table 11.1 You need to add 0.40 to all of the data in column D6. The statistics given there are correct. I get credit for finding that error.
332 Table 11.2 THIS TABLE IS CORRECT AS GIVEN. At least I got something right.
334 middle of page I wrote "variance" when I meant "variation.".
343 Reference to Figure 11.3 This should refer to Figure 11.4.
345 6th line after BUT! Now for a grammer lesson. As I learned in high school, "group" is singular.
350 Reciprocal transformation Dale Berger pointed out that by its very nature, a reciprocal transformation reverses the direction of the scale--high points become low points and vice versa.
359 2nd and 3rd equations John Woodard at Wayne State, who catches a lot of my errors, pointed out that the right side of the numerator on the right ends in 43.346 when it should end in 46.346.
359 2nd equation Then Jodi Goodman came back and pointed out that I typed nΣαj2 when I meant nΣτj2.
359 The second full paragraph I have this all messed up. It should read "For calculating power, most approaches begin with an effect size measure (denoted as d, φ, or f, depending on who is writing). This measure is simply the square root of the variance of the expected population means divided by the expected within-cell variance, which we will estimate with MSerror." Then two lines down change "standard deviation" to "variance." See-- I can even catch my own errors, and this page is one of my worst.
403 Table 12.5 You need to add 0.40 to all of the data in column D6. The statistics given there are correct.
428 Last equation Peter McCormick at St. Francis Xavier Univ. in Canada pointed out that the formula for phi′ αβ is incorrect. He said that one of his "Very!!" bright students once figured out that for all effects, we can define phi′ as √(SSeffect/(N*MSerror)). That is a much simpler way to do the calculation.
527 First paragraph under Sample Size It is R2, and not R, that is equal to p/N-1. Dale Berger also reminded us that if you are testing for the unique contribution of an individual variable, you will need quite large sample sizes if the variables are highly correlated.
538 First equation Laura Gil-Trejo, at Claremont Graduate University, noticed that the divisor in that equation (664.646) came from the reduced model. The correct number is 680.403 from the previous page.I wonder how many editions that wrong number went through.
551 First paragraph Kris Preacher has moved to Vanderbilt. The new link should be
552 Hassles data There is a weird problem that I can no longer explain. The data file has 66 cases, but if you delete the 10 cases where there are no values for the centered variables, the file will produce the results I give. I have no idea why I have negative id scores. I just changed the data, so you may not come across this problem. I think that I have corrected the whole file now. Thanks to Sabry M. Abd-El-Fatta.
575 Third equation Mark Yates, at the University of South Alabama, noted that the equation should read Y = Xb + e. The first + sign is wrong.
626 First equation Mats Nilsson at Stockholm University noted that the second equals sign in that equation should be a minus sign.
627 Variance LogOddsRatio Johan Krabbe at Copenhagen University noticed that the equation should actually be 1/A + 1/B + 1/C + 1/D. I have no idea where my equation came from.
636 Last equation The numerator should begin with a capital sigma. Also due to Johan Krabbe
639 Variance LogOddsRatio See correction for page 627

Answers Exercise 7.25 This is all screwed up. The correct answer is t = 3.186, p = .002
Answers Exercise 7.27 This is all screwed up too. The correct answer is t = 5.00
Answers Exercise 7.49 This is all screwed up because earlier ones were. The correct answer is d = 0.47, using the pretest standard deviation. Katherine Long, at Fordham University, pointed me to the last three errors. No wonder she couldn't get the answer that I gave.


Data Sets

There is a self-extracting archive of all of the data found in Simply click on this link and tell the resulting dialog box where you want to store the download--the desktop is fine. After the file is downloaded, click on the downloaded file and indicate where you want the data files to be stored. Once the data are extracted, you can safely delete the archive file itself. The data are tab delimited with variable names on the first row.


This page was last modified on: 11/21/2016 14:39:37

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