Topic 3

Question 1

What are outliers and how to calculate them from box plots

Answer 1

Outliers values that are uncommonly large or small compared to rest of the data
Usually 1.5 X IQR above the UQ or below the LQ - limits known as fences and values outside them can be identified

Question 2

Frequency density =

Relative Frequency density =

Answer 2

Frequency/interval width

Frequency density / total frequency

Question 3

What is the formula for interpolation?

Answer 3

Lower class boundary + Q - cumul. Frequency/interval frequency X interval width

Question 4

Formula for mean and variance and working out standard deviation

Answer 4

Mean = Sum of xf / sum of f

Variance = sum of xf2 / sum of f - mean2

Standard deviation = root of variance

Question 5

Define Skewness
How to tell if distribution is positively skewed or negatively skewed
Two measures of Skewness

Answer 5

Skewness is term used to describe lack of symmetry in distribution
Positively skewed - Q3-Q2 > Q2 - Q1 and
Mode