Using the data set \"cystfibr\" using the packages ISwR and car in R. Preliminar

Question

Using the data set "cystfibr" using the packages ISwR and car in R.

Preliminary Analysis

Fit a linear model with “pemax” as the response and all other variables as explanatory variables.

List the assumptions of this model.

Interpret the coefficient for Age

Interpret the p-value for Age.

Interpret the coefficient for Sex

Having looked at the relationships illustrated in the matrix scatter plot, does it surprise you that none of the explanatory variables are statistically significant? Why or why not?

Calculate the Variance Inflation Factor (VIF). How might you use this information moving forward?

Explanation / Answer

library(car)
library(ISwR)

d=cystfibr

fit=lm(pemax~age+as.factor(sex)+weight+bmp+fev1+rv+frc+tlc,data=d)
summary(fit)

# coefficient of age is -2.1691 that implies increment of one unit in age gives
nagative 2.1691 effect on pemax

# p-value is 0.646, that is acceptence of age has no effect with the regression

# coefficient of sex is -1.9383 that implies increment of one unit in age gives
nagative 1.9383 effect on pemax

vif(fit)

# here we can note that VIF is for some of coefficient is greater than 10 that imples that
presence of multicolliniarity. So that no coefficent has p-value<0.05, that means regression is not
woorthwhile. we need to remove this multicolliniarity then procced with regression

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