descriptive statistics

Question 1

what are the two types of descriptive statistics?

Answer 1

measures of central tendency
measures of dispersion

^ analyse data 2 help describe, show or summarise it in a meaningful way

Question 2

what are measures of central tendency?

Question 3

name the 3 measures of central tendency

Answer 3

• mode
• mean
• median

Question 4

what is the mean?

and how do you calculate it?

Answer 4

• This is the arithmetic average of all scores
• It is calculated by adding up all the scores and dividing by the total number of scores

Question 5

advantages and disadvantages of using the mean

Answer 5

• adv - can consider all results
• disadv - can be affected by anomalies

Question 6

what is the median?

and how do you calculate it?

Answer 6

the mid point of a set of scores when they are placed in rank order

It is calculated by finding the middle score after placing all the scores in numerical order

Question 7

advantages and disadvantages of using the median

Answer 7

• adv - Not affected by anomalies.
• disadv - doesn’t consider all the results in a set of data, may not accurately reflect it.

Question 8

what is the mode?

and how do you calculate it?

Answer 8

the most frequently occurring score in a set of data

Question 9

what are the advantages and disadvantages of using the mode?

Answer 9

adv - Considers all the results in a set of data, not effected by extreme scores
disadv - doesn’t consider all the results in a set of data, may not accurately reflect it

Question 10

what is a measure of dispersion?

Answer 10

A measure of dispersion shows how far the scores are spread from the measure of central tendency

Question 11

what is standard deviation?

Answer 11

shows how far the scores are spread from the measure of central tendency such as the mean

Question 12

what is the range?

Answer 12

A measure of dispersion which shows the difference between the highest and the lowest scores in a data set

A high range value - scores are spread out
low range value - scores are close together

Question 13

what is a weakness of using the range?

Answer 13

• Affected by extreme scores so may not be an accurate descriptive statistic if there are outliers.
• It doesn’t tell us if the scores are bunched around the mean score or equally distributed around the mean.
• If the a data set has outlying scores it is often better to calculate the standard deviation.

Question 14

what are the strengths of using standard deviation?

Answer 14

all exact values are taken into account, so a precise measure of dispersion