Suppose researchers are interested in the relationship between systolic blood pr
ID: 3389747 • Letter: S
Question
Suppose researchers are interested in the relationship between systolic blood pressure and periodontal disease in a population of low-income families. In order to address the relationship most efficiently, the researchers have decided to model age as a potential confounding variable. During the analysis phase of their investigation, the researchers found it most appropriate to model age as a dummy variable. The variable was quantified in quartiles, and grouped in the following manner.
Category1) Age<25
Category2) Age (25, 35)
Category3) Age (36, 45)
Category4) Age >46
A) Organize these age categories into a set of dummy variables. Describe what a 1 and 0 indicate for each dummy variable.
B) Suppose a multiple linear regression model generated the following results for the dummy variable representing age. Describe the relationship presented.
Parameter Estimates
Variable
DF
Parameter
Estimate
Standard
Error
t Value
Pr > |t|
Intercept
B
0.10811
0.02370
4.56
<.0001
agedummy1
B
0.07642
0.03436
2.22
0.0265
agedummy2
B
-0.02932
0.03452
-0.85
0.3960
agedummy3
B
-0.00421
0.03517
-0.12
0.9047
agedummy4
0
REF
.
.
.
Parameter Estimates
Variable
DF
Parameter
Estimate
Standard
Error
t Value
Pr > |t|
Intercept
B
0.10811
0.02370
4.56
<.0001
agedummy1
B
0.07642
0.03436
2.22
0.0265
agedummy2
B
-0.02932
0.03452
-0.85
0.3960
agedummy3
B
-0.00421
0.03517
-0.12
0.9047
agedummy4
0
REF
.
.
.
Explanation / Answer
a) dummy1 = 1 if age<25
= 0 otherwise
dummy2 = 1 if 25 < age <35
= 0 otherwise
dummy3 = 1 if 36 < age <45
= 0 otherwise
dummy4 = 1 if age > 45
= 0 otherwise
b) y = 0.10811 + 0.07642*(agedummy1) -0.02932*( agedummy2) - 0.00421*(agedummy4)
There is a positive relation between y and agedummy1...and there are negative relation between age and agedummy 2 and between y and age dummy 3 and age dummy 4 does not contribute to y and has no effect to determine y....
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.