Assignment 8.1

Topics: Null hypothesis, Hypothesis, Standard deviation Pages: 2 (353 words) Published: April 21, 2012
Step 1: Solve the following problems.
Use a program (such as MS Word) to write your solutions to the following problems. Use the appropriate t-test to test for significant mean differences in the following research scenarios. Report all relevant information, including hypotheses, degrees of freedom, critical value, and a statement about significance. 1.Dr. Smith conducted an experiment to study the effects of massed versus distributed practice on memory. Twelve participants were randomly assigned to study a short chapter of a history text during either a single 3-hour session or 3 one-hour sessions separated by 24 hours. Twenty-four hours after the study session(s) ended, the participants took an examination on the information in the chapter and the number of correct answers was recorded. Data from that experiment are shown below. Massed PracticeDistributed Practice


X1 = 58.83X2 = 74.67
S1 = 8.50S2 = 7.23
X1 = 58.83 | X2 = 74.67 |
S1 = 8.50 | S2 = 7.23 |
Step 1: H0: x̄1=x̄2 H1: x̄1≠x̄2
Step 2: df= 6+6-2= 10
Step 3: find critical value for t at the .05 level of significance. t crit = 2.228 Step 4: calculate t =4.6
Step 5: compare t to tcrit: Is 4.6 ≥ 2.228? YES! Therefore, we reject the null hypothesis.

2.A researcher wants to see if antihistamines will increase the amount of time in seconds it takes participants to react to a surprise stimulus. He first collects the participants' reaction times while not on antihistamines, and then gives them the dose of antihistamine. One hour later, he collects the participants' reaction times again. Participant IDReaction Time Before AntihistamineReaction Time After Antihistamine 11.371.45

Standard Deviation.68.72
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