Galbraith plot

In statistics, a Galbraith plot (also known as Galbraith's radial plot or just radial plot) is one way of displaying several estimates of the same quantity that have different standard errors. ^[1]

Example for Galbraith's radial plot (A) and a variant of it, the Abanico plot (B) .

It can be used to examine heterogeneity in a meta-analysis, as an alternative or supplement to a forest plot.

A Galbraith plot is produced by first calculating the standardized estimates or z-statistics by dividing each estimate by its standard error (SE). The Galbraith plot is then a scatter plot of each z-statistic (vertical axis) against 1/SE (horizontal axis). Larger studies (with smaller SE and larger 1/SE) will be observed to aggregate away from the origin. ^[2]

See also

• Plot
• Funnel plot

References

1. Galbraith, Rex (1988). "Graphical display of estimates having differing standard errors". Technometrics. 30 (3). Technometrics, Vol. 30, No. 3: 271–281. doi:10.2307/1270081. JSTOR   1270081.
2. University of York, Department of Health sciences MSc course material

External links

• Galbraith plots are available within the metafor package in R, along with various other diagnostic and summary plots.
• MIX 2.0 Software to perform meta-analysis and create Galbraith plots in Excel.
• RadialPlotter Java application for fission track, luminescence and other radial plots from P. Vermeesch.
• RadialPlotter() function within the R package 'numOSL' from Peng Jun for statistical age models analysis in optically stimulated luminescence dating.
• plot_RadialPlot() function within the R package 'Luminescence' to produce Galbraith plots.

Further reading

• Dietze, M., Kreutzer, S., Burow, C., Fuchs, M.C., Fischer, M., Schmidt, C., 2016. The abanico plot: visualising chronometric data with individual standard errors. Quaternary Geochronology 31, 12–18. doi : 10.1016/j.quageo.2015.09.003
• Galbraith, R.F., 1990. The radial plot: Graphical assessment of spread in ages. International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 17 (3), pp. 207–214. doi : 10.1016/1359-0189(90)90036-W.
• Galbraith, R. & Green, P., 1990. Estimating the component ages in a finite mixture. International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 17 (3), pp. 197–206. doi : 10.1016/1359-0189(90)90035-V
• Galbraith, R.F. & Laslett, G.M., 1993. Statistical models for mixed fission track ages. Nuclear Tracks And Radiation Measurements, 21 (4), pp. 459–470. doi : 10.1016/1359-0189(93)90185-C
• Galbraith, R.F., 1994. Some Applications of Radial Plots. Journal of the American Statistical Association, 89 (428), pp. 1232–1242. doi : 10.1080/01621459.1994.10476864 JSTOR   2290987
• Galbraith, R.F., 2010. On plotting OSL equivalent doses. Ancient TL, 28 (1), pp. 1–10. doi : 10.26034/la.atl.2010.433
• Galbraith, R.F. & Roberts, R.G., 2012. Statistical aspects of equivalent dose and error calculation and display in OSL dating: An overview and some recommendations. Quaternary Geochronology, 11, pp. 1–27. doi : 10.1016/j.quageo.2012.04.020