Why are my data plotted with a connecting line, but no symbols?

Prism makes automatic graphs that match the kind of data you entered. If the X column of your data table is formatted for entry of a series of data, Prism plots the data using connecting lines but not symbols. If you enter X values, then Prism plots symbols but no connecting lines.

You can change the way your data are graphed. Double click on any data point (or choose "Change.. Symbols & Lines") to bring up the "Format Symbols and Lines" dialog. There you may choose symbols, connecting lines, or both.