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Test1

Test1 evaluates the fit of the reconciled value for a measurement relative to the tolerance of the measurement. The test divides the calculated measurement correction by the tolerance for the measured value. If the result exceeds the absolute value of 1.0, then the correction is greater than expected, at the 95% confidence level (Section Measurement Confidence Interval).

Where:

Correction = the difference between the reconciled measurement and the measured value. Since Sigmafine derives the measured value from the reconciled measurement, the Correction is positive when the reconciled measurement is greater.

rawtol = the tolerance for the measurement.

ArcErf = inverse normal error distribution function.

ZT \= the number of standard deviations corresponding to the required level of confidence. For 95% level of confidence, ZT = 2.0. You set this value in the Confidence field in the Linear Balance Configuration window.

T = the number of standard deviations for the instrument tolerance. You set this value in the Tolerance field of the Reconciliation Options window.

The following equation shows the approximate calculation for Test 1 when you choose the default conditions for the test: two standard deviations and a confidence level, Zt of two.

Guidelines​

Follow these guidelines when using Test1 to determine if a problem exists in the model.

  • If the result of Test1 is within the range -1 to +1, then the correction is within the tolerance indicated. For example, consider these values.

    Measured value = 100 te

    Reconciled Value = 100.5 te

    Tolerance = 1 te

    And, by the following equation, these values are "good" values.

  • If the result of Test1 is outside the range -1 to +1, then the correction is greater than the tolerance indicated. These values are abnormal and need to be checked.

  • If the result of Test 1 is positive, the reconciled value is greater than the measured value. For example, consider these values.

    Measured value = 100 te

    Reconciled Value = 101.4 te

    Tolerance = 1 te

    And, by the following equation, the result of Test1 is positive.

  • If the result of Test 1 is negative, the measured value is greater than the reconciled value. For example, consider these values.

    Measured value = 100 te

    Reconciled Value = 99.2 te

    Tolerance = 1 te

    And, by the following equation, the result of Test1 is negative.