Data Analysis: Descriptive Statistics

Question 1

Graphs, tables and summary statistics

Answer 1

Help us identify trends and analyse sets of data.

Question 2

Measures of central tendency

Answer 2

• Mean
• Mode
• Median

Question 3

Mean

Answer 3

• Add up all the scores and divide by the total number of scores.
• The most sensitive measure of central tendency. Includes ALL scores.

Question 4

Mean evaluations

Answer 4

• includes all scores - more representative of data as whole.
• Can be distorted by extreme values.

Question 5

Median

Answer 5

• The middle value in a data set when scores are arranged highest to lowest.
• In an even number of scores the median = halfway between the two middle scores.

Question 6

Median evaluation

Answer 6

• Extreme scores don’t affect it and easy to calculate.
• Less sensitive than the mean - not all scores are included in final calculations.

Question 7

Mode

Answer 7

• Most frequently occurring score/ value
• May be more than one mode (bi-modal) or none at all.
• In some data sets = the only method you can use.

Question 8

Mode evaluation

Answer 8

• Easy to calculate.
• Crude measure. Not really representative of data as a whole.

Question 9

Measures of dispersion

Answer 9

• Based on ‘spread of scores.’
• Spread = how far scores vary and differ from one another.
• Range
• Standard deviation

Question 10

Range

Answer 10

Take the lowest value from the highest value plus 1

Question 11

Range evaluations

Answer 11

• Easy to calculate.
• Only takes into account the two most extreme values so may be unrepresentative.

Question 12

Standard deviation

Answer 12

• More sophisticated measure of dispersion.
• Tells us how far the scores deviate from the mean.
• Larger the SD the greater the dispersion or spread within a set of data.
• Large spread = not all participants were affected by the IV in the same way.
• Low SD = data is tightly clustered around the mean. All participants may have responded in a similar way.

Question 13

Standard deviation evaluation

Answer 13

• SD is more precise - includes all values.
• Can easily be distorted by a single extreme value.