Quantitative Data + Data Distributions

Question 1

what should a graph have?

Answer 1

clearly show the findings from the study

short but informative title

both axes should be clearly labelled

the X axis is horizontal and usually represents the independent variable, the Y axis is vertical and usually represents frequency

Question 2

different ways to display quantitative data

Answer 2

tables

bar charts

histograms

line graphs

scattergrams

Question 3

tables

Answer 3

raw data can be set out in a table and/or summarised using measures of central tendency and dispersion

summary tables are more helpful for interpreting findings

Question 4

bar charts

Answer 4

height of each bar represents the frequency of each item

suitable for data that is categorical (nominal, has no particular order) rather than continuous

a space is left between each bar to indicate lack of continuity

Question 5

histogram

Answer 5

similar to a bar chart except that the area within the bars must be proportional to the frequencies represented

the vertical axis must start at zero

the horizontal axis must be continuous

therefore histograms cannot be used to represent categorical or nominal data, there should be no gaps between bars because data is continuous

Question 6

line graphs and scattergrams

Answer 6

a line graph represents continuous data, there is a dot to mark the middle top of where each bar would be and each dot is connected by a line

a scattergram is used for correlational analysis

Question 7

data distributions

Answer 7

normal distribution

negative skewed distribution

positive skewed distribution

Question 8

normal distribution

Answer 8

a symmetrical bell shaped frequency distribution

occurs when certain variables such as IQ are measured and is the predicted distribution when considering an equally likely set of results

most of the scores are clustered close to the midpoint

the mean, median and mode are at the midpoint

dispersion of scores either side of the midpoint is consistent and can be expressed in standard deviations

Question 9

skewed distribution

Answer 9

a distribution is skewed if one tale is longer than the other, signifying that there are a number of extreme values to one side or the other of the mid score

scores are not distributed equally around the mean

Question 11

positive skewed distribution

Answer 11

most scores are clustered towards the left side of the graph (the line is high at the left side of the graph and tails off to the right)

the mode is to the left of the mean because the mean is affected by the extreme scores tailing off to the right

Question 13

negative skewed distribution

Answer 13

most scores are clustered towards the right side of the graph (the line is high at the right side of the graph and tails off to the left)

the mode is to the right of the mean because the mean is affected by the extreme scores tailing off to the left