Question

Suppose a hypertension trial is mounted and 18 participants are randomly assigned to one of the comparison treatments. Each participant takes the assigned medication and their systolic blood pressure (SBP) is recorded after 6 months on the assigned treatment. The data are as follows.

Standard Treatment	Placebo	New Treatment
123	133	113
110	144	118
134	147	121
126	140	123
127	155	124
116	162	130

Is there a difference in mean SBP among treatments? Run the appropriate test at []=0.05.  

Answer 1

Here we use one way anova test ,

Hypothesis:

Ho: There is no difference in mean SBP among treatments.

V/s

H1: There is difference in mean SBP among treatments.

Using excel data analysis toolpack,

Excel => Data => Data Analysis => ANOVA: single factor => input range => ok

Standard Treatment	Placebo	New Treatment
123	133	113
110	144	118
134	147	121
126	140	123
127	155	124
116	162	130

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
Standard Treatment	6	736	122.6667	72.66667
Placebo	6	881	146.8333	108.5667
New Treatment	6	729	121.5	33.1

ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	2454.333	2	1227.167	17.17652	0.000132	3.68232
Within Groups	1071.667	15	71.44444
Total	3526	17

Here p-value = 0.000132 < alpha=0.05 then we reject Ho and conclude that, there is difference in mean SBP among treatments.