Discovering statistics using IBM SPSS statistics by Andy Field, fifth edition – Summary chapter 5

A good graph has the following properties:

1. Shows the data
2. Induce the reader to think about the presented data
3. Avoid distorting data
4. Present many numbers with minimum ink
5. Make large data sets coherent
6. Encourage the reader to compare different pieces of data
7. Reveal the underlying message of data

There are also some graph building guidelines:

1. If plotting two variables, never use 3-D plots
2. Do not use unnecessary patterns in the bars
3. Do not use cylinder shaped bars if that is not functional
4. Properly label the x- and y-axis.

HISTOGRAMS
There are different types of histograms:

1. Simple histogram
   Visualize frequencies of scores for a single variable
2. Stacked histogram
   Compare relative frequencies of scores across groups
3. Frequency polygon
   The same as a simple histogram, but uses a line, instead of a bar
4. Population pyramid
   Comparing distributions across groups and the relative frequencies of scores in two populations.

BOXPLOTS
A box-plot or box-whisker diagram  uses the median as the centre of the plot. It is surrounded by the quartiles which show 25% and 75% of the data. There are several types of boxplots:

1. 1-D boxplot
   A single boxplot for all scores of the chosen outcome
2. Simple boxplot
   Multiple boxplots for the chosen outcome by splitting the data by a categorical variable
3. Clustered boxplot
   A simple boxplot, but it splits the data by a second categorical variable.

BAR CHARTS
Bar charts are often used to display means. There are different types of bars:

1. Simple bar
   The means of scores across different groups or categories.
2. Clustered bar
   Different coloured bars to represent levels of a second grouping variable (e.g: film rating and excitement and enjoyment)
3. Stacked bar
   Clustered bar, but the bars are stacked.
4. Simple 3-D bar
   Second grouping variable is represented by an additional axis
5. Clustered 3-D bar
   A clustered bar, but an extra categorical variable can be added on an extra axis
6. Stacked 3-D bar
   A 3-D clustered bar, but the bars are stacked
7. Simple error bar
   A simple bar chart, but there is no bar, but a line and a dot
8. Clustered error bar
   Clustered bar chart, but a dot with an error band around it.

LINE CHARTS
Line charts are bar charts but with lines instead of bars. There are two types of line charts:

1. Simple line
   The means of scores across different groups of cases
2. Multiple line
   This is equivalent to the clustered bar chart.

SCATTERPLOTS
A scatterplot is a graph that plots each person’s score on one variable against their score on another. There are several types of scatterplots:

1. Simple scatter
   A scatterplot of one continuous variable against another
2. Grouped scatter
   Display points belonging to different groups in different colours
3. Simple 3-D scatter
   A scatterplot of one continuous variable against two others
4. Grouped 3-D scatter
   A scatterplot of one continuous variable against two others but displays different groups in different colours
5. Summary point plot
   A bar chart, but there is a dot instead of a bar
6. Simple dot plot (density plot)
   A histogram, but instead of a summary bar representing frequency scores, individual scores are displayed as dots
7. Scatterplot matrix
   A grid of scatterplots showing the relationship between multiple pairs of variables in each cell of the grid
8. Drop-line
   A clustered bar chart but a dot represents a summary statistic instead of a bar and a line connects the summary of each group