HW5_ans - Chapter 9. The Basics of Experimentation and...

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Chapter 9. The Basics of Experimentation and Testing for a Difference Between Means Name: Class: Date: From Kiess and Green’s Statistical Concepts for the Behavioral Sciences , 4/e Assignment 9.1 The purpose of this assignment is to help you to become more comfortable in recognizing what each statistical symbol and formula in Chapter 9 represents. For each item in the table below, either the term or the definition is given. Complete the table with the missing information. For example, for the between-subjects design , write the definition in the appropriate column. It is best to complete this page without looking at your notes or textbook. Once you have completed it, refer back to your notes and textbook to verify you are correct. Term Definition Between-subjects design Within-subjects design The probability of failing to find a statistically significant difference when one is actually there Obtaining subjects from among people who are accessible or convenient to the researcher Extraneous variables The amount a sample mean differs from its population mean Confound Groups in which the subjects are not expected to differ in any systematic or consistent way Alternative hypothesis Standard deviation of a theoretical sampling distribution of 12 X X Random assignment Developed for measuring the effect of the independent variable on the dependent variable Statistically significant difference
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Chapter 9. The Basics of Experimentation and Testing for a Difference Between Means Name: Class: Date: From Kiess and Green’s Statistical Concepts for the Behavioral Sciences, 4/e Assignment 9.2 The data sets below provide scores obtained from two independent groups of subjects, each group was given a different treatment condition, X 1 and X 2 , respectively. For each data set, calculate a t test for independent groups. Then indicate the decisions you would make for the statistical hypotheses. If you do find a statistically significant difference, calculate the size of that effect. Set A Set B Set C X 1 X 2 X 1 X 2 X 1 X 2 43 39 15 13 540 400 50 37 14 14 460 415 61 35 11 15 600 440 60 38 13 13 520 430 58 40 12 15 430 420 49 36 13 460 Set D Set E Set F X 1 X 2 X 1 X 2 X 1 X 2 91 101 100 98 3 5 92 105 101 105 5 4 95 102 102 110 4 3 96 107 98 96 3 5 98 99 98 5 3
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Chapter 9. The Basics of Experimentation and Testing for a Difference Between Means Answers for Assignment 9.2 Set A X 1 X 2 43 39 50 37 61 35 60 38 58 40 49 36 Sum 321 225 n 6 6 X 53.5 37.5 SS 261.5 17.5 s 2 52.3 3.5 df 10 t +5.25 Reject H 0 Accept H 1 2 η = .66 Set B X 1 X 2 15 13 14 14 11 15 13 13 12 15 13 Sum 78 70 n 6 5 X 13 14 SS 10 4 s 2 2 1 df 9 t –1.32 Fail to reject H 0 Do not accept H 1 No need to calculate 2 η Set D X 1 X 2 91 101 92 105 95 102 96 107 98 Sum 472 415 n 5 4 X 94.40 103.75 SS 33.20 22.75 s 2 8.3 7.58 df 7 t –4.93 Reject H 0 Accept H 1 2 η = .86 Set C X 1 X 2 540 400 460 415 600 440 520 430 430 420 460 Sum 2550 2565 n 5 6 X 510.0 427.5 SS 18000 2187.5 s 2 4500 437.5 df 9 t +2.88 Reject H 0 Accept H 1 2 η = .48
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Chapter 9. The Basics of Experimentation and Testing for a Difference Between Means Set E X 1 X 2 100 98 101 105 102 110 98 96 99 98 Sum 500 507 n 5 5 X 100.0 101.4 SS 10 139.2 s 2 2.5 34.8 df 8 t –0.51 Fail to reject H 0 Do not accept H 1 No need to calculate 2 η
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This note was uploaded on 03/15/2010 for the course PSYCHOLOGY 100B taught by Professor Firstenberg,i. during the Winter '10 term at UCLA.

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HW5_ans - Chapter 9. The Basics of Experimentation and...

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