Descriptive Statistics

Question 1

What is raw data?

Answer 1

How you’ve operationalised variables in order to get a score e.g. measurement, rating scale.

Question 2

State 3 examples of descriptive stats.

Answer 2

Summary statistics.

Measures of dispersion.

Measures of central tendency.

Graphs.

Charts.

Tables.

Question 3

What are inferential statistics?

Answer 3

Statistical analysis, whether or not your findings are significant or whether they could have happened by chance.

Question 4

What are measure of central tendency? What do they do?

Answer 4

Show how the scores cluster round a central point.

They are all averages and give us information about the most typical values in a set of data.

MoCT include mean, median and mode.

Question 5

What is the mean?

Answer 5

Adding up all the scores and dividing by the number of participants in that condition.

Question 6

What is the median?

Answer 6

The ‘middle’ number, of a set of data.

Middle value for a set of odd data.

You must add the 2 middle numbers together and divide by 2, if the data set is even.

Question 7

What is the mode?

Answer 7

The most common/ most frequent value.

Question 8

State an advantage of using the mean.

Answer 8

More sensitive than the median as it makes use of all the values of the data.

It is therefore more representative of the data set as a whole.

Question 9

State an advantage of using the median.

Answer 9

It is not affected by extreme scores, so can give a representative value.

Easy to calculate once you have arranged the numbers in order.

Question 10

State an advantage of using the mode.

Answer 10

It is useful when the data are in categories, such as the number of babies who are securely attached.

Or if I asked your class what their favourite deserts were, it would be the more useful measure.

Question 11

State a disadvantage of using the mean.

Answer 11

It can be misrepresentative if there is an extreme values/outliers.

It might be a value that isn’t one of the actual scores in the data set.

Question 12

State a disadvantage of using the mode.

Answer 12

It is a very crude measure which means it might not be representative of the data as a whole.

Sometimes there can be more than one mode (bi-modal).

Question 13

State a disadvantage of using the median.

Answer 13

It is less sensitive than the mean, as it does not take into account all of the values.

Question 14

What are measures of dispersion?

Answer 14

Includes the range and standard deviation.

These look at how ‘spread out’ the data is.

Question 15

What would a high and a low dispersion mean?

Answer 15

Low dispersion: all scores are similar to the mean.

High dispersion: set contains scores that are considerably higher/ lower than the mean.

Question 16

Outline standard deviation.

Answer 16

The spread of the scores around the mean.

The larger the SD, the larger the spread of scores.

Question 17

How is standard deviation better than the range?

Answer 17

The standard deviation can be better than the range when measuring spread, as it is less affected by extreme values.

It is a more sensitive measure than the range, as it takes into account all scores when calculated.

It allows for the interpretation of individual scores. For example, anyone with an IQ of 121 is in the top 5% of the population, between +2 and +3 SD of the mean.

Question 18

What is a disadvantage of standard deviation?

Answer 18

It is more complicated to calculate (you won’t be asked to calculate a SD for Psychology) and it can be a less meaningful measure if the data isn’t normally distributed.

Question 19

What are percentages?

Answer 19

A type of descriptive statistic that shows the rate, number or amount of something within every 100.

Data can be converted into a percentage by multiplying them as a factor of 100.

For example, a test score of 67 out of a total possible score of 80 would be: 67/80 and then multiply by 100.