Add up all data items and divide by number of data items. Only used with ratio & interval data.
What are measures of central tendency?
Averages- inform us of central values for set of data. Descriptive statistic
What is the median?
Middle value in ordered data list. Used with ratio, interval & ordinal data.
What is the mode?
Value that's most common data item. Used with nominal, interval and ordinal data.
Evaluate mean:
Most sensitive measure as it takes account of exact distance between all values of all data. Easily distorted by extreme values & thus misrepresentative of data as a whole. Can't be used with nominal data or discrete data.
Evaluate median:
Not affected by extreme values so useful under such circumstances. Used with ordinal data & easier to calculate. Not as sensitive as mean as exact values not reflected in median.
Evaluate mode:
Unaffected by extreme values & more useful for discrete data & is only method that can be used with nominal data. Not useful way of describing data when there's several modes.
