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Page Title:
Procedure for Calculating Statistical Control Charts for Ballistic Data |
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|  MIL-J-7093A
(Weps)
Normal Sampling Schedule is outside of the acceptance
limits, the lot shall be rejected.
4.6
Procedure for Calculating Statistical Control Charts for Ballistic Data.
4.6.1
Test data for each basic ballistic parameter to be analyzed shall be
divided in chronological order with respect to firing date into sub-groups of four
samples each, from the series of data being used os the base period. When the
Normal Sampling Schedule is in effect, the first four firings from units selected
from each day's assemblies shall constitute a sub-group. Additional firings from
the same group of units shall not be recorded by the procedures of this paragraph.
4.6.2
From each sub-group of samples, the mean,
, and the range, R,
shall I be computed by the formulas:
Where Xi = individual value for each sample.
4.6.3
The grand mean value, , and the estimated standard deviation,
sX, of X in the base period shall be computed by the formulas:
Where m = number of sub-groups of four in the base period.
Where
is the average range
of the sub-groups in the base
period.
4.6.4
For each parameter to be analyzed, the average value of each
sub-group X, and the range, R, of each sub-group shall be plotted on appropri-
ate graph paper in chronological order with respect to firing date.
On each range chart, the location of the 3 σ control limit (4.6.8)
4.6.5
shall be appropriately indicated.
4.6.6
On each average value chart, the location of the following values
shall be appropriately indicated:
(a) Grand production mean,
(b) Specification limits.
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