A study of cardiovascular risk factors comparing smoking level and gender was fu
ID: 3219780 • Letter: A
Question
A study of cardiovascular risk factors comparing smoking level and gender was funded. There were 25 subjects included in each of the combinations of gender and smoking status. One of the variables measured was the heart rate after six minutes of exercise. A two-way ANOVA is performed with the resulting ANOVA table given below. Source SS DF MS F p-Value Sex 1 331.5 331.5 0.88 0.349 Smoking 2 30850.4 15425.2 41.16 0.000 Interaction 2 341.0 170.5 0.46 0.635 Error 144 53961.1 374.7 Total 149 85484.0
The answer choices are: a) the effect of smoking on heart rate appears to be the same for men and women. (b) there is a strong evidence that the heart rate increases with the amount smoked. (c) interaction has a significant effect which makes it difficult to draw any conclusions. (d) both (a) and (c) are correct.
Explanation / Answer
Lets look at the p values of the variables and the interaction effect
Sex = 0.349 ## not significant
Smoking = 0.000 ## significant
Interaction = 0.635 ### not significant
now we know that an effect is significant only if the p value is less than the assumed alpha , say 0.05 .
as we can see only smoking's p value is less than 0.05 , hence its effect is significant.
C and D can ruled out becuase we know for sure that the interaction effect is not signifcant , so choice C is ruled out . along with it D is ruled out too as C isnt correct
Now B has this " increase" term which may or may not be true .
However A says that men and women do not have any difference wrt heart rate. This is possibly true as our result is not significant and we conclude that the heart rates are not different.
So A.
I guess , the statements make the answer interseting and confusing.
Hope this helps !! Please rate !!
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