In: Math
A scatterplot is the best way to show the mode of a categorical variable. (True/False)
An observational study with a convenience sample provides the strongest evidence that a predictor causes an outcome. (True/False)
Given a normal distribution, find the percentage of observed records that will be within 1.5 standard deviations (1.5 standard deviation to the left AND right of the mean). Show calculations and/or R code used to find your answer.
Scatterplot is the best way to show the mode of a categorical variable. (True) In scatterplot, you can see the number of points per category and the largest line is the mode. So it is easier to show mode.
An observational study with a convenience sample provides the strongest evidence that a predictor causes an outcome. (False) We don’t have any such result which claims that this test is strongest.
Given a normal distribution, find the percentage of observed records that will be within 1.5 standard deviations (1.5 standard deviation to the left AND right of the mean). Show calculations and/or R code used to find your answer.
We use pnorm in r to get the left tailed probability. To get both tailed probability we can just double it since the normal distribution is symmetric around it’s mean.
hence for the standard normal (i.e. normal with mean 0 and variance 1), we have 2*pnorm(1.5)
> 2*pnorm(-1.5)
[1] 0.1336144
So the probability is ~ 0.134