Question

A clinical trial is conducted to compare an experimental medication to placebo to reduce the symptoms of asthma. Two hundred participants are enrolled in the study and randomized to receive either the experimental medication or placebo. The primary outcome is self-reported reduction of symptoms. The data are recorded as follows.

	Change in Symptoms
Treatment	Much Worse	Worse	No change	Better	Much Better
Experimental	11	18	36	29	11
Placebo	13	23	40	11	8

Is there a difference in change in symptoms by treatment group? Run the appropriate test at a 5% level of significance.

Answer 1

Answer in in detail below. please let me know in case you've doubts.

We will perform a Chi-Square test of independence between the treatment and change in symptoms variables.

Here, the contingency table below provides the following information: the observed cell totals, (the expected cell totals) and [the chi-square statistic for each cell.

Below are :

Chi-square statistic, p-value and statement of significance appear beneath the table.

Results
	MuchWorse	Worse	NoChange	Better	MuchBetter	Row Totals
Experimental	11  (12.60)  [0.20]	18  (21.52)  [0.58]	36  (39.90)  [0.38]	29  (21.00)  [3.05]	11  (9.98)  [0.11]	105
Placebo	13  (11.40)  [0.22]	23  (19.48)  [0.64]	40  (36.10)  [0.42]	11  (19.00)  [3.37]	8  (9.02)  [0.12]	95
Column Totals	24	41	76	40	19	200  (Grand Total)

The chi-square statistic is 9.0833.

The p-value is .05905.

The result is not significant at p < .05.

Answer: Since the p-value is NOT less than .05 it means that three is NO difference in change symptoms by treatment groups