1 School of Nursing, Evidence-Based Nursing Center, Lanzhou University, Lanzhou, Gansu, China.Click the details button for more choices about line style, thickness and color. To do this, double clcik on the Y axis to bring up the Format Axis dialog, then enter the Y coordinate (50 or 0.5) and check the option to draw a grid line. How to add a grid line at Y=50% to show median survival Add a grid line at Y=50 or Y=0.5. To prevent the error bars from being superimposed on the staircase curve, the points are connected by regular lines rather than by staircases. The graph on the right shows error bars that show the standard error of the percent survival. This shows the actual survival data very well, as a staircase, but it is cluttered. The graph on the left above shows staircase error envelopes that enclose the 95% confidence interval for survival. Showing error bars or error envelopes make survival graphs more informative, but also more cluttered. The graph on the right plots the data as circles, so you see each subject plotted. The example has two censored subjects in the treated group between 100 and 150 days. You see the ticks clearly at the times when a subject's data was censored. These symbols at the time of death are lost within the vertical part of the staircase. In the left panel, the data are plotted as a tick symbol. Each death is shown as a drop in survival. Graphs without error barsĪs shown above, survival curves are usually plotted as staircases.

If you plot two or more survival analyses on one graph, then the Format Graph dialog doesn't always work and it is best to make the changes on all the Parameters dialogs. If the graph only plots one survival analysis, the two are equivalent. You can change the appearance of the graph either in the Format Graph dialog or the Parameters dialog of nonlinear regression.

Plot fractions or percents? This is simply a matter of preference.

Plot survival or deaths? The former, used more commonly, starts at 100% and goes down.

These choices are straightforward matters of taste: Many are also present in the Parameters dialog for the survival analysis.

Most of the choices are present in both the Welcome dialog and the Format Graph dialog, others are only present in the Format Graph dialog. Prism offers lots of choices when graphing survival data.

Statistics guide for graphpad prism 8