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→How precise is the estimate of Rfree for a certain number of test set reflections?
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and the need to avoid a deleterious effect on the atomic model by omission of too much experimental data. | and the need to avoid a deleterious effect on the atomic model by omission of too much experimental data. | ||
==How precise is the estimate of | ==How precise is the estimate of [[iucr:Free_R_factor|R<sub>free</sub>]] for a certain number of test set reflections?== | ||
The estimate for the relative error of R_free is 1/sqrt(n), where n is the size of the test set. So if n is 1000, and the R_free is 31%, you would expect its relative error to be 31%/sqrt(1000), which is about 1%. | The estimate for the relative error of R_free is 1/sqrt(n), where n is the size of the test set. So if n is 1000, and the R_free is 31%, you would expect its relative error to be 31%/sqrt(1000), which is about 1%. | ||