Descriptive statistics Flashcards
(20 cards)
What are descriptive statistics
The use of graphs, tables and summary statistics to identify trends and analyse sets of data
What are measures of central tendency
A descriptive statistic that provides information about an ‘average’ value for a data set
What are three measures of central tendency
mean, median, mode
What is the mean
The arithmetic average of a data set that takes the exact values of all the data into account
What is the median
The middle value of a data set when the items are placed in rank order
What is the mode
The most frequently occurring value in a set of data
What are measures of dispersion
A descriptive statistic the provides information about how spread out a set of data are
What are the two measures of dispersion
Range and standard deviation
What is the range
The difference between the highest and lowest item in a data set
What is standard deviation
A more sophisticated measure of dispersion. Tells us how much scores deviate from the mean. All differences are added up and divided by the number of scores. This gives a variance and then this is square rooted.
What is a strength of using the mean
Most sensitive measure of central tendency- takes account of exact distance between all the values of all the data
What is a limitation of using the mean
Easily distorted by extreme values= misrepresentative of the data as a whole
What is a strength of using the median
Not affected by extreme scores and easy to calculate
What is a limitation of using the median
Less sensitive than the mean- not all items are included in the final calculation (such as outliers/extreme scores)
What is a strength of using the mode
More useful for nominal (categorical) data
What is a limitation of using the mode
Not always representative of the whole data
What is a strength of using the range
Easy to calculate
What is a limitation of using the range
Only takes into account the two most extreme values- fails to take into account the distribution of numbers
What is a strength of standard deviation
A precise measure of dispersion- takes all the exact values into account
What is a limitation of standard deviation
Can be distorted by extreme values
