bamdit (version 3.4.4)

plotdata: Basic function to plot the data of meta-analysis of diagnostic test

Description

This function plots the true positive rates vs the false positive rates of each study included in the meta-analysis. Study results are displayed by circles, the diameter of each circle is proportional to the sample size of the study (or table). If subgroups are displayed each group is represented by different colours. This function use the package ggplot2.

Usage

plotdata(
  data,
  two.by.two = FALSE,
  group = NULL,
  x.lo = 0,
  x.up = 1,
  y.lo = 0,
  y.up = 1,
  alpha.p = 0.7,
  max.size = 15
)

Arguments

data

Either a data frame with at least 4 columns containing the true positives (tp), number of patients with disease (n1), false positives (fp), number of patients without disease (n2), or for two.by.two = TRUE a data frame where each line contains the diagnostic results as a two by two table, where the column names are: TP, FP, TN, FN.

two.by.two

If TRUE indicates that the diagnostic results are given as: TP, FP, TN, FN.

group

a variable name indicating a group factor

x.lo

lower limit of the x-axis

x.up

upper limit of the x-axis

y.lo

lower limit of the y-axis

y.up

upper limit of the y-axis

alpha.p

transparency of the points

max.size

scale parameter of the maximum size

Examples

## execute analysis
if (FALSE) {

data(ct)
ct$design <- with(ct, factor(design,
             labels = c("Prospective", "Retrospective")))

plotdata(ct,              # Data frame
        group = "design", # Groupping variable
        y.lo = 0.75,      # Lower limit of y-axis
        x.up = 0.75,      # Upper limit of x-axis
        alpha.p = 0.5,    # Transparency of the balls
        max.size = 5)     # Scale the circles
}