Week 3

Question 1

3 types of central tendencies

Answer 1

Mean, median and mode

Question 2

Dispersion

Answer 2

Variance, SD, range

Question 3

How do you work out the range?

Answer 3

Difference between minimum and maximum values.

Question 4

Mode evaluation:

Answer 4

+ not affected by outliers.
- there can be more than one mode, or no mode.

Question 5

Mean evaluation:

Answer 5

+ gives weight to each score
- can be influenced by extreme scores

Question 6

Median evaluation:

Answer 6

+ good to use with ordinal data
+ relatively unaffected by extreme/rouge scores
- less representative for datasets with no/small outliers.

Question 7

What does the variance indicate?

Answer 7

The spread of the whole group of scores.

Question 8

How do you calculate the variance?

Answer 8

1) calculate mean
2) subtract each data point from the mean
3) square each difference from the mean
4) take an average of these numbers (divide by n-1)

Question 9

Limitation of variance

Answer 9

• does not give useful information, calculation always results in high variance.

Question 10

What does standard deviation mean?

Answer 10

Tells us how much all the scores in a data set vary around the mean.
Provides an indication of what is happening between the two extremes of the range.