Interactive dot diagram

Command:

Statistics ROC curves Interactive dot diagram

Description

In addition to the ROC curve, MedCalc offers a second graphical display to visualize the accuracy of a diagnostic test, namely an Interactive dot diagram.

Required input

• Variable: select the variable of interest.
• Classification variable: select a dichotomous variable indicating diagnosis (0=negative, 1=positive).
  If your data are coded differently, you can use the Define status tool to recode your data.
• Filter: (optionally) a filter in order to include only a selected subgroup of cases (e.g. AGE>21, SEX="Male").
• Options: Logarithmic transformation of data.

Graph

In the graph the data of the negative and positive groups are displayed as dots on two vertical axes. Initially, a horizontal line indicates the cut-off point with the best separation (minimal false negative and false positive results) between the two groups. The corresponding test characteristics sensitivity and specificity are shown at the right side of the display.

By clicking in the display, you can move the horizontal line to other values or cut-off points.

See also

• ROC curves: Introduction
• Plot versus criterion values
• Predictive values
• Interval likelihood ratios
• Comparison of ROC curves
• Format graph
• Graph legend
• Add graphical objects
• Reference lines