Do left-handed people live shorter lives than right-handed people? A study of th

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).

1.   For each of the F statistics given, find the degrees of freedom and an approximate P-value. Summarize the results of these tests. (Use Sentences for Answer)

_________________________________________

2. Using the information given, write a short summary of the results of the study. (Use Sentences for Answer)

_____________________________________________

Explanation / Answer

(1) For handedness, the degrees of freedom = dfh = 2 - 1 = 1

For gender, the degrees of freedom = dfg = 2 - 1 = 1

For interaction , the degrees of freedom = dfh * dfg = 1

For error, the degrees of freedom = (949-1) - dfh - dfg - dfh * dfg

= (949-1) - 1 - 1 - 1

=945

For handedness, p-value is

P( F1,945 > 22.36) = 0.000015 ( < 5%)

So handedness would be used to determine if there is a difference in the mean age at death.

For gender, p-value is

P( F1,945 > 37.44) = 0.000015 ( < 5%)

So gender would be used to determine if there is a difference in the mean age at death.

For interaction , p-value is

P( F1,945 > 2.10) = 0.15 ( > 5%)

So it would not be used to determine if there is interaction between handedness and gender.

(2) From the above results of the study, it can be infered that there is statistically significant difference in the mean age at death between male and female.

Also it can be infered that there is statistically significant difference in the mean age at death between left-handed and right-handed.

However, the interaction between handedness and gender can't be used.

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.