Question

Here is the scenario that I am working on:

The efficacy of a new addiction medication was evaluated in a randomized, placebo-controlled, doubleblind study. The medication in question, Antaquil, is intended to moderate the symptoms of alcohol withdrawal and craving with minimum side effects. Over the course of three weeks, a sample of 36 individuals who were recovering from alcohol addiction were randomly assigned to two groups: one administered the medication and one administered a placebo. At the end of the designated period, participants were administered the Obsessive Compulsive Drinking Scale (OCDS), an instrument that provides a global measure of thoughts about alcohol during nondrinking periods. Scores can range from 0 to 40 with higher scores signaling higher levels of rumination about alcohol. Prior to participation participants were all informed of the nature of Antaquil and were told they could leave the study at any time. Outcome data on the OCDS are shown below (also found in the Data Set Scenario 4 Excel file).

treatment group 40, 35, 27,18,30,28,11,23,30,13,16,17,26,22,19,17,29,10

placebo group 37,35,34,24,29,14,23,25,32,37,30,30,29,22,23,31,28,20

I need to know what the data analysis statistical procedures are  

Answer 1

To carry out this test firstly we will check equality of variance assumption :

By using Excel's data analysis tool pack

Since P value= 0.1826 > 0.05 therefore NOT SIGNIFICANT . We can assume that variances are EQUAL.

NULL HYPOTHESIS H0:

ALTERNATIVE HYPOTHESIS Ha:

Let mu1 be the mean population for treatment.

Let mu2 be the mean population for Placebo

Level of significance=0.05

test statistic t= -2.08

P value=0.0225

Since P value smaller than the level of significance 0.05 therefore SIGNIFICANT.

Decision: REJECT NULL HYPOTHESIS H0.

Conclusion: We have sufficient evidence to conclude that the Population mean for treatment is smaller than the Population mean for Placebo at 0.05 level of significance. It means who takes treatment think less about Alcohol as compared to placebo.