Do left-handed people live shorter lives than right-handed people? A study of th
ID: 3221931 • Letter: D
Question
Do left-handed people live shorter lives than right-handed people? A study of this question examined a sample of 949 death records and contacted next of kin to determine handedness. Note that there are many possible definitions of "left-handed." The researchers examined the effects of different definitions on the results of their analysis and found that their conclusions were not sensitive to the exact definition used. For the results presented here, people were defined to be right-handed if they wrote, drew, and threw a ball with the right hand. All others were defined to be left-handed. People were classified by gender (female or male) and handedness (left or right), and a 2 × 2 ANOVA was run with the age at death as the response variable. The F statistics were 22.36 (handedness), 37.44 (gender), and 2.10 (interaction). The following marginal mean ages at death (in years) were reported: 77.39 (females), 71.32 (males), 75.00 (right-handed), and 66.03 (left-handed).
(a) For each of the F statistics given, find the degrees of freedom and an approximate P-value. Summarize the results of these tests.
(b) Using the information given, write a short summary of the results of the study.
Explanation / Answer
Answer:
Do left-handed people live shorter lives than right-handed people? A study of this question examined a sample of 949 death records and contacted next of kin to determine handedness. Note that there are many possible definitions of "left-handed." The researchers examined the effects of different definitions on the results of their analysis and found that their conclusions were not sensitive to the exact definition used. For the results presented here, people were defined to be right-handed if they wrote, drew, and threw a ball with the right hand. All others were defined to be left-handed. People were classified by gender (female or male) and handedness (left or right), and a 2 × 2 ANOVA was run with the age at death as the response variable. The F statistics were 22.36 (handedness), 37.44 (gender), and 2.10 (interaction). The following marginal mean ages at death (in years) were reported: 77.39 (females), 71.32 (males), 75.00 (right-handed), and 66.03 (left-handed).
source
Df
F
P
Gender
1
37.44
0.0000
Handedness
1
22.36
0.0000
Interaction
1
2.10
0.1476
Error
945
Total
948
(b) Using the information given, write a short summary of the results of the study.
There is significant effect of gender on age at death, F(1,945)=37.44, P=0.0000.
There is significant effect of handedness on age at death, F(1,945)=22.36, P=0.0000.
There is no significant effect of interaction between gender and handedness on age at death, F(1,945)=2.10, P=0.1476.
source
Df
F
P
Gender
1
37.44
0.0000
Handedness
1
22.36
0.0000
Interaction
1
2.10
0.1476
Error
945
Total
948
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