Question

Reduced heart rate variability (HRV) is known to be a predictor of mortality after a heart attack. One measure of HRV is the average of normal-to-normal beat interval (in milliseconds) for a 24-hour time period. Twenty-two heart attack patients who were dog owners and 50 heart attack patients who did not own a dog participated in a study of the effect of pet ownership on HRV, resulting in the summary statistics shown in the accompanying table.

Measure of HRV (average normal-to-normal beat interval)

	Mean	Standard Deviation
Owns Dog	875	137
Does Not Own Dog	803	134

The authors of this paper used a two-sample t test to test H₀: μ₁ - μ₂ = 0 versus H_a: μ₁ - μ₂ ≠ 0.
(a) What assumptions must be made in order for this to be an appropriate method of analysis?
We must assume that the population of  ---Select--- dog owners non dog owners is  ---Select--- is is not approximately normal and we must also assume that the samples are  ---Select--- not independent independent of each other.

(b) The paper indicates that the null hypothesis was rejected and reports that the P-value is less than 0.05. Carry out the two-sample t test. What is your p-value rounded to 3 decimal places?  


(c) Is your conclusion consistent with that of the paper?

YesNo    

Answer 1