Pro’s of using the mode
Easy to find, can be used with qualitative and quantitative data, unaffected by extreme values, always a value in the data
What’s the mode?
The most common value
Con’s of using the mode
Might be no mode or more than one mode, can’t be used to calculate measures of spread
Pro’s of using the median
Easy to calculate, unaffected by outliers, best to use with skewed data
What’s the median
The middle value
Con’s of using the median
May not be a value in the set of data
Pro’s of using the mean
Uses all the data, can be used to calculate standard deviation and skew
What’s the mean
The sum of the values divided by the number of values
Con’s of using the mean
May not be a value in the set of data, always affected by extreme values, can be distorted by open-ended classes
How to calculate an outlier
What’s the standard deviation
How much the individual values differ from the mean
How to calculate skew
(3*(mean-median))/standard deviation
How do you compare data sets?
Using a measure of average, spread or skewness
How do you compare averages?
… for data A is larger than … for data B, so on average data A is more …
How do you compare spread?
… for data A is larger than that of data B so data A is less consistent than data B
What does a positive skew mean?
Majority of results were low with few higher results
What does negative skew mean?
Majority of results were high with few lower results