Matched Pairs Analysis

A matched pairs analysis compares the average score during baseline and a summary score during the trial for each finding.

An analysis of sodium levels in a group of patients treated with either nicardipine (red, left) or a placebo (blue, right) is shown below. Each point represents an individual patient.

A measure of the average of the baseline and trial values is plotted along the x-axis. The vertical line represents the population mean. Points lying to the right have values higher than the population average, points to the left are lower.

A measure of the difference between these values is plotted on the y-axis. The horizontal line indicates the position where no measured difference exists between baseline and post-treatment values. Points lying above the line show increased levels in response to treatment, points lying below show decreased levels.

The mean value for the lab, normalized against its baseline value, is located at the intersection of the vertical and horizontal red lines. The diamonds show the extent of the variation in the measurements.

In this example, although nicardipine treatment appears to have no effect on absolute levels of sodium in patients, it does tend to reduce the variation between patients.