As part of a study investigating symptoms mountain climbers experience at high a
ID: 3312413 • Letter: A
Question
As part of a study investigating symptoms mountain climbers experience at high altitudes, researchers looked at the skeletal muscle tissue of a random sample of climbers. Each trained for two weeks on a bicycle, either at a normal oxygen supply or under hypoxic conditions corresponding to an altitude of 13,000 ft. They also were assigned to train at either a high or low level of energy expenditure. The percent change in vascular endothelial growth factor mRNA was measured and all relevant assumptions were confirmed. Below is a table of their results:
How many climbers were there in this study?
Write an appropriate conclusion for each main effect and the interaction between oxygen supply and energy expenditure on growth factor mRNA.
Below is an interaction plot for this analysis. Explain how the plot above confirms the results for the interaction term in the ANOVA table.
high or low level of energy expenditure. The percent chan vth factor mRNA was measured and all relevant assumptio ow is a table of their results Effect value 1, 6016.05 0.001 0.207 D- O2 Supply Energy Expenditure 1,605.780.009 O2 Supply*Energy Exp.1, 60 1.14 ny climbers were there in this study? (lpt)Explanation / Answer
(a)
There are 2 groups for the main effect O2 supply. So, a = 2
There are 2 groups for the main effect Energy expenditure. So, b = 2
The degees of freedom for main effect O2 supply sum of squares = a - 1 =1
The degees of freedom for main effect Energy expenditure sum of squares = b -1 =1
The degrees of freedom for interaction effect = (a-1)*(b-1) = 1
The degees of freedom for error sum of squares = ab(n-1)
Given that this degees of freedom = 60
So, (n-1) * 2 * 2 = 60
=> n = 16
Hence, there were 16 climbers in the study.
(b)
The p - value for the main effects O2 supply and energy expenditure are very low and thus, they are statistically significant.
However, the p-value for the interaction effect (0.207) is higher than 0.05 and is statistically not significant.
Thus, the main effects O2 upply and energy expenditure significantly affect the percent change in vascular endothelial growth factor mRNA but their intercation effect does not significantly affect the percent change in vascular endothelial growth factor mRNA.
(c)
The interaction plots for this analysis are non - intersecting.
The percent change in vascular endothelial growth factor mRNA is higher when the oxygen supply is hypoxic than when it is normal, for both the level of expenditure.
Since, the interation plots for this analysis are non - intersecting, it confirms the result mentioned above that the interaction effect of O2 supply and energy expenditure, is not statistically significant.
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