Foreword
Foreword to 1959 printing
Introduction
Section 1
Scope of the publication
Section 2
Illustration of general problems by examples
1. Example 1. Tensile strength of malleable iron
castings
2. Example 2. Breaking strength of cloth
3. Example 3. Ash-content in samples of coal
Section 3
Introduction to the simpler statistical tools
4. Definitions
5. The presentation of data
Dot diagram
Frequency distribution
Example A. Percentage ash-content in 250 test
analysis of coal
Example B. Tensile strength in malleable iron
castings
Example C. Depth of sapwood in telephone poles
6. Use of the mean and the standard deviation in
scaling a frequency distribution. The Normal curve
Section 4
Sampling and statistical theory
7. Statistical uniformity and random sampling; levels
of control
8. Sampling methods in practice
Section 5
Statistical theory and specification
9. The statistical concept of a population
10. The basis of securing conformity to specification
(a) By a system of tests of samples
(b) By requiring that records are kept which will
provide statistical evidence of the level of
control of the processes of manufacture
Considerations of importance to user
Considerations of importance to the producer
Section 6
The statistical relationship between sample and batch
11. The variation of the mean and the standard deviation
in samples
Theoretical formulae
(a) Variation of means
(b) Variation of standard deviations
12. The reliability of a mean estimated from a repre-
sentative sample; duplicate sampling
Estimate of reliability of a mean obtained from a
comparison of duplicate samples
13. Illustration of the use of the mean strength, and
the strength of the weakest strip, in a sample of
prescribed size, in specifying the quality of cloth
14. Fiducial or confidence limits for means, standard
deviations and coefficients of variation
15. Simultaneous variation in the mean and the standard
deviation
Section 7
Further examples of the use of statistical methods in
securing conformity with specifications by consignment
sampling
16. Systems of grading or classifying
(i) Grading by the mean and the standard deviation
(ii) Grading by the mean and the coefficient of
variation
(iii) Grading based on a lower limit
17. The efficiency of a classification applied to random
samples from consignments
Section 8
Control charts
18. Statistical analysis as a tool for locating sources
of trouble; assignable and chance causes of
variation
19. The basis of the control charts; methods of
estimating sigma
Methods of obtaining sigma e
(a) Estimate of sigma from the mean value of the
squared standard deviations
(b) Estimate of sigma from the mean value of the
standard deviation
(c) Estimate of sigma from the mean value of the
range
20. Description of the different forms of chart
(a) The chart for means
(b) The chart for standard deviations
(c) The chart for coefficients of variation
(d) The chart for range
21. General remarks on the interpretation of the charts
22. Example 1. Ash-content in coal
23. Example 2. Lamp quality
24. Example 3. Quality of a manufactured chemical
25. Example 4. Breaking strength of a roofing material
Section 9
Performance tests and indices of quality
26. The statistical concept of correlation
Appendices
I. Definitions
II. Definitions
III. The calculation of the mean and the standard
deviation
IV. The Normal curve; its equation and probability
tables
V. Further constants and tables associated with the
Normal distribution
VI. Methods of testing whether the variation in a
quality characteristic is Normal or not
VII. Errors arising from the use of the tables of
control limits and confidence limits owing to lack
of Normality in the variation of a characteristic
VIII.Statistical reference books, tables and British
Standards
Figures
1 & 2. Malleable iron castings
3. Breaking strength in pounds of cotton fabric strips
4. Ash-content in coal samples
5. Histograms of frequency distributions
6. Illustration of approach to limit
7. Diagram indicating types of variation in samples
8. Ash-content in coal. Simultaneous variation in
means and standard deviations (samples of 10)
9. Types of grading
10. Specification levels
11. Diagram illustrating the use of the limits of a
control chart to detect changes in the level of
control
12. Control charts: percentage of ash in coal
13. Control charts for length of life of lamps of
marked voltage.
14. Control chart, product D
15. Breaking strength of a roofing material
16. Correlation between hardness and strength
17. Comparison of the normal with an asymmetrical or
skew curve
Tables
1. Tensile strength in pounds per square inch of
malleable iron castings
2. 75 test results of malleable iron castings
corresponding to source 4 rearranged in order from
min. to max.
3. Breaking strength, in pounds, of cotton fabric
strips
4. Ash-content data: means in groups of 10 tests
5. Frequency distributions
6. Percentage of observations falling outside limits
determined by the standard deviation
7. Ash-content data: standard deviations and means in
groups of 10 tests
8. Ash-content data: frequency distribution of means
and standard deviations in groups of 10 tests
9. Cloth samples: testing rule based on mean of sample
10. Cloth samples: testing rule based on weakest strip
in sample
11. Fiducial or confidence limits
12. Compressive strengths of sand lime bricks in lb.
per sq. in.
13. Factors for calculation of control limits for mean,
standard deviation, and coefficient of variation
14. Factors for calculation of control limits for range
15. Percentage ash-content in two coals
16. Lamp data: length of life at marked voltage in hours
(5 lamps in a sample)
17. Lamp data: illustrating the calculation of sigma e
18. Product D: statistical constants relating to control
charts
19. Calculation of standard deviation. Schemes A and B
20. Calculation of standard deviation. Scheme C
21. Squares of numbers, 1-300
22. Tables of the Normal probability curve
(1) Values of chances for intervals of 0.1 of t
(2) Values of t corresponding to certain simple
chances
23. Estimate of sigma from the mean deviaiton of small
samples
24. Further frequency distributions
25. Application of a rough test of Normality
26. Effect on control limits of non-normal variation