Descriptive Statistics

What are descriptive statistics?

Statistics that are used to summarise and analyse quantitative data to draw meaningful conclusions

What are the two types of descriptive statistics?

measures of central tendency and measures of dispersion

What are the three measures of central tendency?

mean, median, mode

What is the mode?

most frequently occurring score in a data set, easy to identify but isn't representative of the data as a whole

What is the median?

the middle value in a set of scores when arranged from highest to lowest, when there's an even number the 2 middle scores are averaged

What is a strength of using median?

not affected by extreme scores, easy to calculate

What is a weakness of using median?

Less representative as not all scores are included in the final calculation

What is the mean?

the average of scores in the data set

What is a strength of using mean?

It is the most representative of the measure of CT as it includes all scores in a data set

What is a weakness of using mean?

Can be distorted by extreme values

What are the two measures of dispersion?

range and standard deviation

What is the range?

the difference between the highest and lowest scores in a distribution

What is a strength of using range?

Easy to calculate

What is a weakness of using range?

based on only 2 scores, so isn't that representative of the data set

What is standard deviation?

a computed measure of how much scores vary around the mean score

What does a high standard deviation signify?

indicates a greater spread of data around the mean

What does a low standard deviation signify?

scores are tightly clustered around the mean

What is a strength of using standard deviation?

Includes all values in the final calculation - more sophisticated measurement

What is a weakness of using standard deviation?

Not easy to calculate and there's a risk of it being affected by an extreme value