An epidemiologist was interested in examining the effects of three factors on an
ID: 3150463 • Letter: A
Question
An epidemiologist was interested in examining the effects of three factors on an obese person’s cholesterol levels. Let xi , i = 1, 2, 3, represent the effects of the three factors, respectively, and y be the total cholesterol. The following output was generated using statistical software.
Regression Analysis
S = 14.01 R-Sq = 95.1% R-Sq(adj) = 92.1
Analysis of Variance
a)Does the regression model appear to be useful? State the null and alternative hypotheses of interest, the critical and calculated test statistic, and justify your answer. (Use = 0.05.)
b. Construct a 2-sided 95% confidence interval for (male vs female). State the null and alternative hypotheses of interest, and interpret your confidence interval.
c. Obtain a point prediction of the cholesterol for a male who exercises 2 days a week >= 60 minutes, but is not a vegetarian.
d. Use the values of SSR and Total SS in the results to calculate R2. Compare this value to the one given in the results.
e. Interpret the coefficient and test statistic for the ‘exercise’ factor in the model.
predictor Coef Stdev T P constant 225.19 65.70 3.43 0.019 male vs femal 12.725 3.570 3.56 0.016 vegetarian vs Non-vegetarian -39.45 23.24 -1.70 0.150 Number od days with >= 60 min exercise -33.48 12.29 -2.73 0.042Explanation / Answer
ANSWER:
Null hypothesis: The three factors are equally effective on an obese's person cholesterol levels( no difference in three factors)
ALTERNATIVE HYPOTHESIS:
There was a significant difference between three factors (factors are not eually effective
F table value at 5% level of significnce with (3,5) degrees of freddom is 5.4095
therefore Fcal = 32.19<Ftab 5.4095
hence there was a signinificant difference between three facors
that ios factors were not equally effective
alternative hypothesis was accepted
(B) The 95% C.I. is (-71.8649,4.9049)
(C) R2=95.1% means 95.1% of the variatin in the cholesterol levels were explained by the variables sex and exercise.
(E) Exercise coefficent was found to be statisticalyy significant and the coefficient was negative means(-33.48) it was inversely related with cholesterol levels