The Show Legends checkbox in this section provides a “master” control to specify if legends will - or will not - be displayed on the graph. Other options on this page allow you to specify if Individual legends for Fill Color and Size should be used or if a Combined Fill Color and Size legend should be used.
If you choose to display Individual legends for Fill Color and Size, options to turn on or off these legends separately will be provided via the Fill Color and Size checkboxes. Note that the checkbox control for these two options are shared with checkboxes found on the individual pages for Fill Color and Size options.
Combined Fill Color and Size legend will only be available if combining these two legends makes sense. Unlike other graphs that Prism generates, there are many situations in which multiple legends may need to be displayed to convey the relevant information being displayed on the graph. For example, if the Symbol Fill Color and Symbol Size are defined by different continuous variables, then a legend for Fill Color and a legend for Size will both need to be displayed to fully understand what is being displayed on the graph. On the opposite end of complexity, if both Symbol Fill Color and Symbol Size are set to “One for the entire graph”, then a single Combined (Fill & Size) legend is capable of summarizing all of the information shown on the graph (in fact, by default, a legend wouldn’t even be shown for this graph due to the limited complexity of the data being displayed).The easiest way to figure out if a combined legend makes sense is to consider the following two questions:
•Is Symbol Fill Color defined by a continuous variable?
•Are the variables defining Symbol Fill Color and Symbol Size different?
If the answer to either of those questions is “Yes”, then a Combined Fill Color and Size legend will NOT be possible. If this option is not possible, then the option will be “grayed out” and you will not be able to select it on this page (or in the list of pages on the left side of the dialog).
