Hi,
This plot was created using the GraphBuilder module in JMP where the "% Cell Labeled" (as a continuous variable) was used for the Y-axis, and the Time (day) (as a continuous variable) was used for the X-Axis. If this makes sense, please proceed; otherwise, I would recommend reading the "Discovering JMP" and "GraphBuilder" tutorial (found under the Help menu).
To display both the dots and the line of fit, select the Scatter Plot and the Fit Line display options (by holding the SHIFT key; see below)
Finally, to set the reference line (green line), double-click on the plot's Y Axis, go to the Reference Lines section, enter 88 for Value, Line Color > Green, Line Style > 2, and click Add (see below)
Best,
TS
Thierry R. Sornasse