IPC-TM-650 EN 2022 试验方法1.pdf - 第27页
Measurement Systems Analysis For Binary Data Test Effectiveness Calculator Version 1.0, August 2002 Introduction Welcome to the Measurement Precision Calculator. This utility is intended to perform the calculations for M…
The final results are summarized and totaled on the scorecard.
The scorecard shows the total number of dispositions in each category for each tester. All testers are summed on the right
side on the table.
Below the scorecard is another table summarizing the number of tests performed, the number of good parts, the number of
bad parts, and the number of testers.
The final section shows the test effectiveness calculation.
The first metric is the overall test effectiveness. This is a percentage, showing what portion of the dispositions were per-
formed correctly. A rule of thumb is that in a good test, the dispositions must be performed correctly at least 90% of the
time. Any test effectiveness less than 80% would be unacceptable. In this case the result is in the middle zone, where
improvement is recommended.
The next metric is the percent of good parts falsely rejected. In good tests, the false reject rate would be less than 5%. Any
test with a false reject rate greater than 10% needs improvement, which is the case here.
The final metric is the probability of passing bad parts. In a good test the false accept rate should be less than 2%. Any false
accept rate greater than 5% should be improved. That is the case here.
These results should be compared to the goals for the effectiveness of this inspection or test. These goals should be based
on the criticality of the outcome and probable impact of incorrect disposition.
The final step is to determine lessons learned from the MSA and document any changes to the test procedure. If the evalu-
ation indicates the test procedure needs to be improved, these improvement projects should be undertaken as soon as pos-
sible.
Measurement System Scorecard
1 2 3
4
5 6 7
8 9 10
8 7 9 0 0
0 0
0 0 0 24
2 2 1 0 0
0 0
0 0 0 5
0 1 0 0 0
0 0
0 0 0 1
30
6
4
3
Total tests
# of testers
Total
Tester
Results
Good parts
Bad parts
Dispositioned
Correctly
Good and
Rejected
Bad and
Accepted
Measurement System Effectiveness
Criteria Result Conclusion
80.0
27.8
8.3
Test effectiveness (%)
Probability of false rejects
(%)
Probability of false
acceptance (%)
Marginal
Needs improvement
Needs improvement
5
Measurement Systems Analysis For Binary Data
Test Effectiveness Calculator
Version 1.0, August 2002
Introduction
Welcome to the Measurement Precision Calculator. This utility is intended to
perform the calculations for Measurement Precision Studies as described
in the IPC test method IPC-TM 1.8.
This unility is useful for situations where the measurement data is recorded
in binary format,, such as pass/fail or go/no-go.
Please refer to the test method before beginning the measurement precision study.
The test method defines the terms and equations used in detail.
Refer to the User Guide for further detailed instructions.
This workbook includes the following
- A blank spreadsheet to enter measurements
- A spreadsheet with example data
- A form for manual data entry, if desired.
The test data should be entered into the yellow areas on the
data entry spreadsheet. Code results as "A" and "R".
This is a beta version of this software.
Your comments and suggestions would be appreciated.
If you have any questions, please contact:
Figure 1 Measurement Repeatibility and Reproducibility
Repeatibility
Reproducibility
Accuracy
Accuracy
Reproducibility
Repeatibility
How close is the
measurement to the
true value?
True
value
How close are a series of
measurements by several
people on the same part on
the same equipment?
True
value
True
value
How close is a series of
measurements on one
part by one person?
Operator A
Operator C
Operator
B
Page 1 of 10