Q.6.119 - Elementary Statistics

Question

How is a normal probability plot used to detect outliers? 

Step-by-Step Solution

Answer

The outlier is seen in the usual probability plot.

Step 1: Given Information

Consider the "probability of normalcy plot."

A probability distribution about the mean, indicating that data near the mean occur more frequently than those further from it

Step 2: Explanation

The normalcy probability plot is a graphical method for determining whether or not data is normally distributed. The line is constructed between observed variable values and normal scores. Outliers and odd values are detected using the probability plot.

Normal values are those that fall along the probability line.

Outliers are data values that exist outside the pattern (line) of the data.