6.6 assessing normality

Question 1

what is a QQ plot?

Answer 1

quantile-quantile plot or
normal probability plot or
normal quantile plot
a graph of points (x,y) where each x value is from the original set of sample data, and each y value, it corresponding z-score that is a quantile value expected from the standard normal distribution

Question 2

how can you use a histogram to assess normality?

Answer 2

visually inspect the histogram: does it approximate a bell shape? if yes, then it is normal, if no, then not

Question 3

what are the axis in a QQ plot?

Answer 3

x is original data

y is z-score

Question 4

how can you use outliers to assess normality?

Answer 4

if there are more than 1 outlier, assume it is not a normal distribution

Question 5

how can you use a QQ plot to assess normality?

Answer 5

if the pattern of the points is reasonably close to a straight line and the points do not show a systemic pattern that is not a straight line, then it is normal