Measures of Central Tendency and Dispersion

Question 1

What are descriptive statistics?

Answer 1

The use of graphs, tables and summary statistics to identify trends and analyse sets of data

Question 2

Mean

Answer 2

The mathematical average, calculated by adding all values in a set of data and dividing them by the number of values

Question 3

Median

Answer 3

The central value in a set of data when values are arranged from lowest to highest. The median can be half way between numbers

Question 4

Mode

Answer 4

The most frequently occurring value in a set of data. The data could be bi-modal or have no mode

Question 5

Range

Answer 5

The spread of scores, calculated by subtracting the lowest from the highest value of the data set

Question 6

Standard deviation

Answer 6

A single value that tells us how far scores deviate away from the mean. The larger the standard deviation, the greater the dispersion within a set of data

Question 7

Scattergram

Answer 7

A graph that represents the strength and direction of the relationship between co-variables in a correlational analysis

Question 8

Bar chart

Answer 8

A graph in which the frequency of each variable is represented by the height of the bars. Can be used for discrete data

Question 9

Histogram

Answer 9

A graph where the area of the bars represent frequency. The x-axis must start at true zero and the scale is continuous

Question 10

Normal distribution curve

Answer 10

A symmetrical, bell shaped curve. The mean, median and mode occupy the same midpoint

Question 11

Positive skew

Answer 11

Where most of the distribution is concentrated towards the left of the graph, resulting in a long tail on the right. The mean and median are right of the mode (higher values than the mode)

Question 12

Negative skew

Answer 12

Where most of the distribution is concentrated towards the right of the graph, resulting in a long tail on the left. The mean and median are left of the mode (lower values than the mode)