• In the lower plot, apparent age (x-axis) is plotted versus the summation of the normal distribution of each individual analyses (Deino and Potts, 1992). This is roughly comparable to a histogram plot.
• Auxilliary plots can include: moles of ³⁹Ar_K released per crystal, radiogenic yield, K/Ca ratio, Cl/K ratio (not pictured), as well as the age±error for the individual data points.
• The probability distribution diagram is most useful for displaying single-crystal laser-fusion data to assess the distribution of the population. Individual analyses which fall outside a distinct population are easily identified. These outlyers can included xenocrysts, seperate mineral phases, altered grains and/or laboratory contaminants. In the above plot, a number of sanidine grains define a population at approximately 26.1 Ma (blue). An anomalously old grain at ~27.8 Ma (red) can easily be identified as plagioclase due to it's comparitively low K/Ca ratio and ³⁹Ar_K yield.

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Deino, A., and Potts, R., 1992. Age-probability spectra from examination of single-crystal ⁴⁰Ar/³⁹Ar dating results: Examples from Olorgesailie, Southern Kenya Rift, Quat. International, 13/14, 47-53.

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