Presentation and Display of quantitative data: graphs, tables, scattergrams, bar charts

Why do researchers use tables?

To present the summary findings of their research.

What are raw scores?

An unconverted measurement e.g. a participant scores 15 on a memory test: this is their raw score.

• These aren’t shown in the table as they must be converted to descriptive statistics to present an overview of the results

What are descriptive statistics?

Numerical ways of summarising and describing raw scores so patterns and trends are easier to see.

• Measures of central tendency: mean, median, mode

• Measures of dispersion: range, standard deviation

What is the data on the x-axis of a bar chart?

Discrete (not continuous) - data that consists of separate, fixed values that can’t be divided or fall in between numbers, it’s usually counted, not measured.

• E.g. scores on a memory test, number of ‘yes’ answers ticked on a questionnaire

What type of data does a bar chart deal with?

Categorical data, which doesn’t necessarily fall into any particular order.

Do bar charts have gaps?

What does the x-axis show on a bar chart?

The categories/conditions.

What does the y-axis show on a bar chart?

The score/percentage per category/condition.

What does the x-axis represent on a histogram?

The categories that have been measured.

• E.g. the number of marks in a psychology exam across one year group

What does the y-axis show on a histogram?

The frequencies of each category occurring.

• E.g. The frequency of full marks on question 5 on the exam

What does a histogram show?

Continuous data.

• Any category with zero frequency is represented by a space (a gap) in the chart

Do histograms have gaps between the bars?

What is a scattergram used to do?

To display the results of correlations.

• It shows the point at which two separate pieces of data meet

In a scattergram, does it matter which co-variable is placed on the x- or y-axis?

No. Either co-variable can be placed on either axis, and this does not affect the direction or strength of the correlation (e.g. a strong positive correlation will still be shown).

Tips for drawing graphs.

• Axes should be clearly labelled

• Correct plotting of points or bars

• Detailed title

• Appropriate choice of scale