Numerical Methods of Summarizing Data

Percentages & Proportions

These are the most commonly used numerical measures for summarizing data. The formulas are given below.

Where;

f – the frequency or the number of cases in any category

N- the total number of cases in all categories.

Ratio

Used to compare categories in terms of relative frequency. The formula is given below;

Where;

- the number of cases in the first category

- the number of cases in the second category

Rates

Rates are defined as the number of actual occurrences of some phenomenon divided by the number of possible occurrences per some unit of time. The formula is given below;

Rate of change or percentage change

Is useful for comparing the actual change between time periods.

Where;

– frequency at the new/current time period

– frequency at the old/previous time period