Question

Explain what you would look for in a data set that would indicate the set is normally distributed. Provide examples of a normal distribution and explain your rationale.

Answer 1

The factors to be analyzed that would indicate that the data set is normally distributed are:

• There are no outliers in the data set.
• The data is not skewed.
• The data has a bell-shaped curve when plotted.
• To check the normality of the data set, we can use the Anderson-Darling test or Shapiro-Wilk test.

Example:

The data is:

Bin	Frequency
36-38	2
38-40	4
40-42	10
42-44	15
44-46	19
46-48	19
48-50	15
50-52	10
52-54	4
54-56	2

What biological or environmental factors, that act independently and additively, contribute to the normalcy of wing lengths?

The histogram is:

Housefly Wing Lengths Frequency 36 38 40 42 50 52 54 56 44 46 48 Length (x.1mm)

The data has a bell-curve, so it is normally distributed.