# All about Analysis in SPSS What I need to know and why? What makes a good graph? Show the data. Induce the reader to think about the data being presented (rather than some other aspect of the graph, like how pink it is). Avoid distorting the data. Present many numbers with minimum ink. Make large data sets (assuming you have one) coherent. Encourage the reader to compare different pieces

of data. Reveal data. Tufte (2001) 3-D effect Patterns

Cylindrical bars Badly labelled y-axis A 2-D plot

Informative y-axis Distractions Minimum ink

Graphs chart Builder 2 ways Gallery Element by element Simple histogram Select a variable from the list and drag it into x-axis

Stacked histogram (grouping) Frequency polygon Population pyramid (grouping) Element Properties: To change statistic Set Parameters: To set Bins

Characteristics SBP: Single variable for different categories CBP: To add a second categorical variable

1-DBP: single variables with no categorical differences Outliers Potential Outliers a normal distribution in wed expect

about 5% to have absolute values greater than 1.96 (we often use 2 for convenience), and 1% to have absolute values greater than 2.58, and none to be greater than about 3.29. Simple bar: To see the means of scores across different groups of cases. For example, you might want to plot the mean ratings of two films.

Clustered bar: A second grouping variable. For example, ratings of the two films, but for each film have a bar representing ratings of excitement and another bar showing ratings of enjoyment. Stacked bar: Same as the clustered bar except that the different coloured bars are stacked on top of each other rather than being side Simple 3-D bar: by side. Clustered 3-D bar: Also the same as the clustered bar except that the second grouping variable is by an additional axis. This is like the clustered bar chart above except that you can

add a third categorical variable on an extra axis. The means will almost certainly be impossible for anyone to read on this Stacked 3-D bar: type of graph so dont use it. This graph is the same as the clustered 3-D graph except the Simple error bar: different coloured bars are stacked on top of each This is the same as the simple bar chart except that instead of bars the mean is represented by a dot, and a line represents the precision of the estimate of the mean (usually Clustered error bar: the 95% confidence interval is plotted, but you can plot the standard deviation or standard error of the mean also).

This is the same as the clustered bar chart except that the mean is displayed as a dot with an error bar around it. Simple line: To see the means of scores across different groups of cases Multiple line: Equivalent to the clustered bar chart to plot means of a particular variable but

produce different-coloured lines for each level of a second variable Simple scatter: Grouped scatter: Simple 3-D scatter: Grouped 3-D scatter:

Summary point plot: Simple dot plot: Scatterplot matrix: Drop-line:

To plot values of one continuous variable against another. like a simple scatterplot except that you can display points belonging to different groups in different colours (or symbols). 1st in 3-D 2nd in 3-D Same as a bar chart except that a dot is used instead of a bar. Also known as density plot, similar to a histogram except that rather than having a summary bar representing the frequency of scores, a density plot shows each individual

score as a dot. Useful, like a histogram, for looking at the shape of a distribution. A grid of scatterplots showing the relationships between multiple pairs of variables. Similar to a clustered bar chart but with a dot representing a summary statistic (e.g. the mean) instead of a bar, and with a line connecting means of different groups. These graphs can be useful for comparing statistics, such as the mean, across different groups.