3.2 Central Tendency And Spread Flashcards
Measure of location
A single value which describes a position in a data set
Measure of central tendency
When a single value describes the centre of the data
When to use mode
This is used when data is qualitative, or quantitative with either a single mode or two modes (bimodal). It is not very informative if each value occurs only once.
When to use median
This is used for quantitative data. It is usually used when there are extreme values, as they do not affect it.
When to use mean
This is used for quantitative data and uses all the pieces of data. It therefore gives a true measure of the data. However, it is affected by extreme values.
Equation for mean in general
Equation for mean dealing with frequency table
Equation for mean dealing with two sets
Adv and disav of mean
Adv
- reflects all the data
Disadv
- can be affected by extreme values
Adv and disadv of median
Adv
- isn’t affected by extreme values, outliers or errors
Disadv
- doesn’t use all the data
Adv and disadv of mode
Adv
- can be used for qualitative data
- isn’t usually affected by extreme values, outliers or errors
Disadv
- doesn’t use all the data
- not representative if other values have similar frequencies or if total frequency is small
Adv and disadv if range
Adv
- reflects all the data
Disadv
- can be affected by extreme values
Adv and disadv of IQR
Adv
- isn’t usually affected by extreme values
Disadv
- doesn’t use all the data
Examples of measure of central tendency
- Mean
- Median
- Mode
Examples of measure of spread
- Range
- IQR
- Standard deviation
Standard deviation equation for calculator
Standard deviation for raw data
Standard deviation for frequency tables
Standard deviation equation dealing with a set sample size
