EXPERIMENT LAB 1 40 students were recruited to participate in an experiment. The

Question

EXPERIMENT LAB 1 40 students were recruited to participate in an experiment. They were equally, randomik B a so- treatment group and control group. In the experiment group, subjects were askt p memory test; they were then asked to drink a 12-ounce guarana drink, and then as asked to perform yet another 50-item memory test. The 20 treatment group results are given below as (name, before score, after score) Sam, 17, 4o Jim, 28, 32 Suzy, 13,21 Gwen, 48,49 Laura, 25,21 George, 45,41 Larry, 33,33 Dave,23,27 June, 33,49 Liz, 33,12 Harold, 44,39 Ben, 23, 25 Elke,19,19 Julius, 37,34 Ken, 24,29 Sarah, 42,44 Paula 22,21 Jerry, 34,37 Cari, 13,14 Jill, 43,48 In the control group, the subjects were given the memory test, then they waited awhile, a given the second memory test. Their results: Chris, 13, 19 Perri 34,32 Ashour, 41,37 Jenny, 31,31 Peter, 22,17 Eddie, 23,45 John, 17,13 Sophie, 41,40 Sasha, 34,49 Gary, 12,13 Frank, 34,36 Ann, 23,21 Julie, 34,33 Nancy, 22,19 Lucy, 4442 Hera, 49,50 Jeet, 44,43 Nestor, 33,38 Quinn, 43,34 Mansour, 12,11 Using the procedure outlined in lecture, tell me (with 95% CONFIDENCE) whether guarana drinks affect memory. Show all your work. Submit to your instructor's email by NOON MONDAY. Use the subject line "experiment lab 1(your Name)"

Explanation / Answer

From information given, d1bar=2.35, d2bar=0.75, d=after-before, sd1=7.35, sd2=6.99, n1=20, n2=20, where, dbar denotes mean difference, sd denotes standard deviation of difference, and n is sample size, 1 and 2 denote treatment and control group respectively.

The 95% c.i for population mean difference in score is:(d1bar-d2bar)+-talpha/2, df=38 sqrt[sd1^2/n1+sd2^2/n2]

=(2.35-0.75)+-2.02sqrt[7.35^2/20+6.99^2/20]

=(-2.99, 6.19)

The 95% c.i contains 0, therefore, fail to reject null hypothesis [H0:mu1-mu2=0 (guarana drinks doesnot affect memory], and conclude that there is insufficient sample evidence that guarana drinks affect memory.

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