Descriptive statistics Flashcards
What are measures of central tendency?
A central or typical value of a set of values
What is the mean?
An arithmetic average of a set of scores calculated by dividing the sum of the scores by the number of scores
What are strengths of the mean?
It takes all scores into account so it is the most sensitive measure
What are limitations of the mean?
- Easily distorted by extreme scores, making it unrepresentative
- Can give a peculiar measure that cannot represent reality
What is the median?
The middle values of a set of score when ordered in ascending order
What are strengths of using the median?
More representative than the mean, especially with small data sets
Unaffected by extreme scores in one direction
What are weaknesses of using the median?
Less representative when the data set is polarised eg has one extreme high and one extreme low
What is the mode?
The most frequently occurring value in a set of scores
What are the strengths of the mode?
unaffected by extreme scores
Most useful with a large data set
What are the weaknesses of the mode?
Unreliable for use with small data sets as small changes to scores can result in it being multimodal
What are measures of dispersion?
Values which give an indication of how spread out a set of scores are
What is the range?
A measure of dispersion that is the difference between the highest and the lowest scores
What are strengths of using the range?
Easy to calculate and give an indication
Useful when the median is being used as an average as the range uses the top and bottom as a set and median is the middle number
What are weaknesses of using the range?
Easily distorted by extreme scores
Only uses two numbers from the data set no matter how large the data set is so is a basic indicator of spread
No indication of the spread of scores within a data set
What is standard deviation?
a measure of dispersion that shows how much each score in the data set deviates on average from the mean of that data set
