Social Research Glossary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Home
Citation reference: Harvey, L., 2012-24, Social Research Glossary, Quality Research International, http://www.qualityresearchinternational.com/socialresearch/
This is a dynamic glossary and the author would welcome any e-mail suggestions for additions or amendments.
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Pictorial representation
Pictorial respresentation refers to various graphical ways of depicting data sets.
A bar chart is a diagram for displaying nominal or ordinal scale data.
Bar charts indicate frequencies by the length of columns or horizontal bars. For each category in the data a bar is drawn from the horizontal axis (or left-hand axis) proportional to the number of observations in the category. The varying heights (or lengths) convey an impression of the relative importance of each category. The bars are all made the same width and are often separated from each other along the axis to emphasize the discrete nature of the categories. They may be placed in any order along this axis when nominal data are involved.
Often bar charts include pictorial representations (e.g. rows of figures, cars, pound notes etc.)
Cumulative bar charts can be used to show the breakdown of some total into component parts.
Pie charts are used to represent the proportions of a total accounted for by different values of a variable or different components of an entity (or record). Thus relative frequencies are pictured by a circular 'pie' cut into pieces. The 360 degrees of the circle being divided into the appropriate values for the variable. So, for example if there were 50 women and 100 men in a sample, the gender proportions on the pie chart would be a 'slice' with a 120 degree angle at the centre for women (50/150x360) and 240 degrees for men.
A histogram is a diagram that represent a frequency distribution of data measured on an inverval or ratio scale. Blocks are raised above each interval or category along the horizontal axis. The width of each block is made proportional to the size of the interval and the height of each block is adjusted until the area is proportional to the relative frequency.
Histograms imply a set of continuous data and so the columns are placed next to each other, the end of one being the start point of the next.
A picturegram is any graphical representation of data that relies on putting data into pictorial form for comparison purposes.
Graphs are usually line graphs in which a series of points are joined to imply a continuous development : e.g. a daily temperature graph recorded over a month.
More precisely, a graph is a scaled representation of how one variable relates to one or more others. Two-dimensional graphs are the most common. These have two axes usually, but not always, placed at right angles to each other. One of the variables to be plotted is scaled along each of the axes. In the space, set points, are plotted for each and every observation, displaying their values on the two dimensions simultaneously. By convention any independent variable is placed along the horizontal axis (x-axis) and the dependent variable along the vertical axis (y-axis). (Economists often reverse this convention, having price on the vertical axis and the quantity of commodity bought on the horizontal axis.)
Misleading impressions can be given by altering scales on the axes
Scattergram
A scattergram is the plot of the co-ordinates of a bivariate relationship. It provides a picture of a relationship between the two variables, usually prior to some form of regression or correlation analysis.
Conventionally the independent variable is plotted on the horizontal (X) axis and the dependent variable on the vertical (Y) axis. The scattergram may provide clues to the nature of the relationship (linear, curvilinear, zero).
See also
Researching the Real World Section 8.3.12.3
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