Lecture 4

Question 1

How to establish intervals?

Answer 1

(max(value) - min (value)) / number of classes

Question 2

Location

Answer 2

Tells us something about the average or typical individual (i.e. where the observations are centered)

Question 3

Spread

Answer 3

Tells us how variable the measurements are from individual to individual - how widely scattered the observations are around the center

Question 4

Arithmetic mean

Answer 4

An algorithm, process or sets of rules to be followed in calculations - sum of all the observations in a sample divided by n, the number of observations

Question 5

Population mean

Answer 5

Mean of all possible samples from a population

Question 6

Standard deviation

Answer 6

Commonly used measure of the spread of a distribution. It measures how far from the mean the observations typically are. The standard deviation is large if most observations are far from the mean, and it is small if most measurements lie close to the mean.

Question 7

Median

Answer 7

Middle measures of a set of observations (distributions)

• Odd number of observations: Median is the middle value
• Even number of observations: Median calculated = [Y(n/2) + Y(n/2+1)]/2

Question 8

Symmetric distributions [Mean - Median]

Answer 8

• Uniform: Mean equals the median

- Bell-shaped: Mean equals the median

Question 9

Bimodal [Mean - Median]

Answer 9

Median smaller than the mean

Question 10

Skewed-left [Mean - Median]

Answer 10

Mean smaller than median

Question 11

Skewed-right [Mean - Median]

Answer 11

Mean greater than the median