pare the ratio with an F distribution on 2 and 2B degrees of freedom. Assuming that the FBI has as many as 500 estimates, the 5% critical point from an F distribution on two and 1,000 degrees of freedom is 3.005. Thus, if a given standard deviation is times larger than the pooled standard deviation for that element, one should consider remeasuring that element, in that the precision may be larger than expected by chance alone (5% of the time).

REFERENCES

1. Carriquiry, A.; Daniels, M.; and Stern, H. “Statistical Treatment of Case Evidence: Analysis of Bullet Lead”, Unpublished report, 2002.

2. Antle, C.E. “Lognormal distribution” in Encyclopedia of Statistical Sciences, Vol 5, Kotz, S.; Johnson, N. L.; and Read, C. B., Eds.; Wiley: New York, NY, 1985, pp. 134–136.

3. Wellek, S. Testing Statistical Hypotheses of Equivalence Chapman and Hall: New York, NY 2003.

4. Ku, H.H. Notes on the use of propagation of error formulas, Journal of Research of the National Bureau of Standards-C. Engineering and Instrumentation, 70C(4), 263–273. Reprinted in Precision Measurement and Calibration: Selected NBS Papers on Statistical Concepts and Procedures, NBS Special Publication 300, Vol. 1, H.H. Ku, Ed., 1969, 331–341.

5. Cameron, J.E. “Error analysis” in Encyclopedia of Statistical Sciences, Vol 2, Kotz, S.; Johnson, N. L.; and Read, C. B., Eds., Wiley: New York, NY, 1982, pp. 545–541.

6. Mood, A.; Graybill, F.; and Boes, D. Introduction to the Theory of Statistics, Third Edition McGraw-Hill: New York, NY, 1974.

7. Vardeman, S. B. and Jobe, J. M. Statistical Quality Assurance Methods for Engineers, Wiley: New York, NY, 1999.



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