The type of table one should use to represent data depends upon the type of data that are to be shared. Three basic types of data are interval, ordinal and nominal. Interval data are also referred to as quantitative or numerical data, and include numbers. Examples of interval data include distances, weights, heights, and other measurements. Ordinal data are also number-based, but the data are in serial order. For example, rating-scale surveys, in which participants rate an item or experience as poor, fair, good or excellent, are used to elicit ordinal data. Nominal data are also known as categorical or qualitative data. Nominal data are not number-based, using words and categories instead.
Because the categories of nominal data have no meaningful numerical value, the best way to represent them is through frequency distribution. A frequency distribution shows how often each possible variable shows up in the data. From this information, the researcher can determine median values of the data set, or which variables appear most often. Relative frequency distribution is created by dividing the frequency of each variable by the total number of observations. These frequency distribution tables can be used to create pie charts, bar graphs and other graphic displays.
Because they are numerical in nature, interval data can be represented in multiple ways. The most popular method for displaying interval data is the histogram. Before you can create a histogram, you must determine the frequency distribution for the data set. The data must be divided into classes determined by the creator. Then you can create a histogram that shows the number of responses that fall into each class. This will result in a bar graph-like visual representation. Histograms are helpful for showing the distribution of the data, such as the normal curve that represents the distribution of human intelligence. Another method for displaying numerical data is the stem and leaf display. This type of display breaks number data into smaller parts to show the data. For example, percentage data could be displayed by breaking the 10s and ones into stems and leaves. The stems of zero to 10 are listed vertically. The data are listed according to the ones place of the number data or leaves, and listed horizontally out from the stem. A score of 98 would have a stem of nine and a leaf of eight. The stem and leaf display allows the researcher to show each number involved in the data set. Scatter plots are a type of visual display used to show smaller data sets. A dot is used to represent each data point collected. This can show the extremes of the data in the set.
Ordinal data, because it must be kept in order, can be shown using the same methods as other numerical data as long as the order is retained. Frequency distributions are helpful, but must maintain the order values.