PART 1: Independent Measures These first questions are about estimating how many participants you need in your study for obtaining a Power level of 80% (since that is the minimum desired for ALL items in this worksheet}. (Table S-) 5. You want to conduct a study to see if males and females diifer on their levels of math anxiety. You plan to give all participants a math anxiety test and compare the two groups. You will analyze tlte data using an independent measures Host and predict there will be a difference [not stating if one will be better or worse. thus. it is a non-directional hypothesis). You select your alpha level at a = .dS and do a rwodtailed test. The only previous research you can nd notes an effect size of d = .2-5. How many participants will you need in each group {malestfemales} to obtain a power level of sons 5. You completed the study in #5 and your actual obtained effect size was at - .50. You decide to replicate the study with two new groups of participants. You still plan to give all participants a math anxiety test and compare the two groups. You will analyze the data using an independent measures Heat and hypothesize there will be a difference (not stating it' one will be better or worse, thus. it is again a non-directional hypothesis]. You select your alpha level at rt = .05 and do a two-tailed test. How many participants will you need in each group to obtain a power level of 80%? These next questions are about estimating how much power your study had based on the obtained effect size ofyour study and how many participants you had per group. (Table 8-5] '1 You conduct a study to see ifmales and females differ on their levels of math anxiety. All participants [3t]! males and 3t] females) completed a matlt anxiety test and you compared the two groups using an independent measures Host, and hypothesized tltere will be a difference (not stating if one will be better or worse. thus. it is a non-directional hypothesis). You select your alpha level at o = .ll and do a two-tailed test. The effect size obtained was moderate (medium) at a\" = .50. How much power did your study have? Is this an acceptable amount of power to condently reject the null (and say there truly is a difference)? If yes, good. If no, how could you fix it so that you at least reach 80% power (or more)? 8. You replicated the study in #'i'. and you still had 3t] participants per group (it) male. 3t} female}, though this time you obtained effect size of d = .80. You still gave all participants a math anxiety test and compared the two groups using an independent measures r-test. and predicted there will be a difference [not stating if one will be boner or worse, thus. it is a nous directional hypothesis). You kept your alpha level at u - .05 and did a two-tailed test. How much power did your study have? Is this an acceptable amount of power to condently reject the null {and say there truly is a difference)?r If yes. good. If no. how could you x it? Power Activity: Independent Measures The following two tables are only for INDEPENDENT Measures. You'll see the word "Independent" in the title of the table. Therefore, if you need Dependent Measures tables, check the other set of tables in this worksheet. Also check each table to verify if it is estimating Power/EffectSize/SampleSize. Answer all "Independent" questions using these two tables. You will have two questions per table. Table 8-5 Approximate Power for Studies Using the t Test for Independent Means Testing Hypotheses at the .05 Significance Level Number of Participants Effect Size in Each Group Small (.20) Medium (.50) Large (.80) One-tailed test 10 11 .29 53 20 .15 .46 80 30 .19 . 61 92 40 .22 .72 97 50 .26 .80 .99 100 41 .97 * Two-tailed test 10 .07 .18 39 20 .09 .33 69 30 .12 .47 86 40 .14 .60 94 50 .17 .70 98 100 .29 .94 "Nearly 1 Table 8-6 Approximate Number of Participants Needed in Each Group (Assuming Equal Sample Sizes) for 80% Power for the / Test for Independent Means, Testing Hypotheses at the .05 Significance Level Effect Size Small (.20) Medium (.50) Large (.80) One-tailed 310 50 20 Two-tailed 393 64 26