Presentation and Display of Quantitative Data

• One way of representing data is in the form of a summary table. It is important to remember when tables appear in the results section of a report they are no longer raw scores but have been converted to descriptive statistics.
• Bar Charts:


  Bar charts are used when data is divided into categories (we call this discrete data.) There are usually two conditioned and these occupy the horizontal x-axis. The frequency or amount of each category is plotted on the vertical y-axis. Bars are separate on a bar chart as conditions are separate from each other.
• Histograms:


  In a histogram the bars touch each other which shows that data is continuous rather than discrete. The x axis is made up of equal sized intervals of a single category. For example, percentage scores in a maths test is broken down into intervals such as 0-9, 10-19, 20-29 etc. The y axis represents the frequency within each interval. If there was a zero frequency for one of the intervals, the interval remains without a bar.
• Line Graph:


  Line graphs also represent continuous data rather than discrete to show how something changes in value. Typically the IV is plotted on the x axis and the DV on the y axis. Used when data is over time.
• Scattergrams


  Scattergrams do not depict differences but associations between co-variables. Each co-variable occupies an axis, does not matter which and each point on the graph corresponds to the x and y position of co variables. A correlation coefficient is a statistics that describes the relationship between two sets of paired data. The correlation coefficient tells you essentially the same thing as a scattergram; whether two variables are related and, if so, how strongly their relationship is positive or negative. Correlation coefficients are always numbers between -1 and +1.