types of data

nominal data is also referred to as

categorical data

nominal data defintion

• where numbers usually refer to people in categories

• how frequently something occurs

example of nominal data

how many people are right handed and left handed

appropriate descriptive statistics for nominal data

• percentage

• ratio

• pie chart

• bar chart

ordinal data defintion

• where the scores obtained are on a numerical scale

• can be out in rank order

• however the units of measurement are not of equal, definable size

• usually based on opinion so tend to be subjective rather than objective

appropriate descriptive statistics for ordinal data

• mean

• mode

• ratio

• percentage

• line graph

• histogram

• pie chart

interval data defintion

• data is on a numerical scale with unit of equal, definable data

• data is objective e.g. reaction time, height

appropriate descriptive statistics for interval data

• mean

• median

• mode

strengths of nominal data

• easy to generate from closed questions, so large amount of data collected increasing reliability

• quick to find mode to assess central tendency

weaknesses of nominal data

• without linear scale ppts are unable to express degrees of response

• can only use mode as a measure of spread, no median and mean

strengths of ordinal data

• more informative rather than nominal data

• easy to generate from likert and rating scales

• median can be used as on linear scale, as well as mode

weaknesses of ordinal data

• gaps between the groups are only relative - so comparisons may be invalid as ppts may interpret the scale differently

• gaps between groups are not equal so a mean cannot be used to assess central tendency

strengths of interval data

• more informative - points are directly comparable because they are equal

• easy to generate from closed questions

• scientific measurement - highly reliable

weaknesses of interval data

• in interval scales that are not scientific measures there is no absolute baseline

• this means scoring zero may not mean the ppt does not demonstrate that variable at all, merely may mean than the scale does not measure it