library(rstanarm)
library(easystats)
library(tidyverse)
mtcars-simple3
regression
en
bayes
frequentist
qm1
stats-nutshell
qm2
mtcars
Exercise
We will use the dataset mtcars
in this exercise.
Assume your causal model of your research dictates that fuel economy is a linear function of horse power, cylinder count and displacement of the engine.
Which of the predictors in the above model has the weakest causal impact on the output variable?
Notes:
- Use can either use frequentist or bayesian modeling.
- Use R for all computations.
- There are multiple ways to find a solution.
Answerlist
cyl
hp
disp
- All are equally strong
- none of the above
Solution
In order to gauge the relative importance of the predictors, we need to make sure they are on the same scale:
<-
mtcars2 standardise(mtcars)
Compute Model:
<- lm(mpg ~ hp + cyl + disp, data = mtcars2)
lm1_freq <- stan_glm(mpg ~ hp + cyl + disp, data = mtcars2, refresh = 0) lm1_bayes
Get parameters:
parameters(lm1_bayes)
Parameter | Median | CI | CI_low | CI_high | pd | Rhat | ESS | Prior_Distribution | Prior_Location | Prior_Scale |
---|---|---|---|---|---|---|---|---|---|---|
(Intercept) | 0.0047118 | 0.95 | -0.1832279 | 0.1820132 | 0.51900 | 1.0000771 | 3300.694 | normal | 0 | 2.5 |
hp | -0.1720874 | 0.95 | -0.5041621 | 0.1767126 | 0.83475 | 1.0000367 | 2899.518 | normal | 0 | 2.5 |
cyl | -0.3703854 | 0.95 | -0.8421462 | 0.1282401 | 0.93225 | 0.9997860 | 2144.550 | normal | 0 | 2.5 |
disp | -0.3829240 | 0.95 | -0.8228923 | 0.0476500 | 0.96125 | 0.9998687 | 2447.111 | normal | 0 | 2.5 |
Note that the absolute value of the coefficient’s estimate is what we are after.
The predictors with the strongest impact is disp
, and cyl
. The weakest influence has hp
.
Answerlist
- wrong
- correct
- wrong
- wrong
- wrong
Categories:
- regression
- en
- bayes
- frequentist
- qm1
- stats-nutshell