Please explain using excel worksheet and indicate formulas in the explanation. T
ID: 3253699 • Letter: P
Question
Please explain using excel worksheet and indicate formulas in the explanation. Thank you .
An observational study is conducted to investigate the association between age and total serum cholesterol. The correlation is estimated at r = 0.35. The study involves n=125 participants and the mean (std dev) age is 44.3 (10.0) years with an age range of 35 to 55 years, and mean (std dev) total cholesterol is 202.8 (38.4).
a) Estimate the equation of the line that best describes the association between age (as the independent variable) and total serum cholesterol.
b) Estimate the total serum cholesterol for a 50-year old person.
c) Estimate the total serum cholesterol for a 70-year old person.
Explanation / Answer
Given data - We can incorporate in excel as below format;
a) To estimate the equation of lie that best describes the association between age and total serum cholestrol.
b1 = slope = r * (Std dev y / Std dev x)
We can do above formula calculation in excel by selecting respective cells from the data we prepared for respective terms in formula.
b1 = 0.35 * (38.4 / 10.0) = 1.344
b0 = intercept = mean of y - (b1*mean of x)
= 202.8 - ( 1.344 * 44.3 ) = 143.261
Thus the equation line is ; y = b0 + b1*x
y = 143.261 + 1.344 x
Thus above data in excel can be modified as -
b) To estimate total serum cholestrol for age = 50 years
y = 143.261 + 1.344 * 50
y = 210.461
Thus total serum cholestrol for 50 year old person is 210.461
We can use the cells from updated data in excel for respective terms in formula.
c) To estimate total serum cholestrol for age = 70 years
y = 143.261 + 1.344 * 50
y = 237.341
Thus total serum cholestrol for 70 year old person is 237.341
x y 35-45 years Cholestrol mean 44.3 202.8 St Deviation 10 38.4 r 0.35