A new procedure for calculating the precision and accuracy of end-member reactions is presented that accounts for the kinetics of reaction progress and possible displacements between the experimental and true P-T reference frames. Application to recently collected experimental data indicates that the estimated precision (1σ) of the position of an end-member reaction at metamorphic temperatures (~900 K) using a single set of experimental data may be ± 100 to ± 310 bars and that a minimum estimate of accuracy (1σ) may be on the order of ±270 to ±410 bars, depending on how precisely the reaction is bracketed and assuming 1σ potential systematic errors in pressure and temperature of ±250 bars and ±5 °C, respectively. The accuracy of the grossular-anorthite-kyanite-quartz (GASP) reaction position using five different studies is estimated to be between ±350 and ±380 bars (1σ) at 900 K, depending on whether the individual studies were calibrated using independent standards.

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First page of Error propagation for barometers; 1, Accuracy and precision of experimentally located end-member reactions
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