methods of presenting data

what do graphs and charts do?

provide a means of seeing the findings at a glance

write down the features of a table

→the numbers you collect are referred to as raw data

• they are usually summarised using measures of central tendency and dispersion

write down the features of a bar chart

→the height of the bar represents frequency

• bar charts are mostly suitable for data that’s not continuous, specifically nominal data

• data is set out in distinct categories

• in bar charts, spaces are left between each bar to indicate the lack of continuity

write the features of a histogram

→similar to bar charts except the area within the bar must be proportional to the frequencies represented

• vertical axis must begin at 0

• horizontal axis must be continuous

• there should be no spaces between the bars

write down the features of line graphs

→the y-axis represents frequency but, like a histogram, the values along the x-axis must be continuous

• data that have some implicit order, such as numerical data

what are normal distributions

when measuring certain variables, the frequency of these measurements should form a bell-shaped curve

features of normal distribution

• the bell shape is symmetrical

• most people are represented in the middle of the curve, with the mean, median and mode occupying the centre point

what are skewed distributions?

not all distributions are balanced/symmetrical

desscribe a positively skewed distribution?

• most of the distribution is concerntrated towards the left of the graph, with a long tail off to the right

• this shows people scoring lower than average

• mean is higher than median

negative skew?

• most of the distribution is concerntrated towards the right of the graph, with a long tail off to the left

• this happens when most scores are high

• median is higher than the mean

ways to improve data

→get a larger sample

→adjust the difficulty to produce appropiate results