JB/T 3736.4-1994 Normal probability paper, a statistical tool commonly used in quality management

This standard describes the composition, drawing and application of normal probability paper. Normal probability paper is suitable for inferring whether the observed value comes from a normally distributed population, estimating the mean, standard deviation and defective rate of the population, etc. JB/T 3736.4-1994 Commonly used statistical tools in quality management Normal probability paper JB/T3736.4-1994 Standard download decompression password: www.bzxz.net

Machinery Industry Standard of the People's Republic of China
JB/T 3736. 1--3736. 8-94
Statistical tools commonly used in quality management
Published on December 9, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on January 1, 1995
Mechanical Industry Standard of the People's Republic of China
Statistical tools commonly used in quality management
Normal probability paper
1 Subject content and scope of application
This standard describes the composition, drawing and application of normal probability paper. JB/T 3736.4-94
Replaces JB3736.4-84
Normal probability paper is suitable for inferring that the observed value is from a normal distribution population, estimating the mean, standard deviation and defective rate of the population, etc.
2 Composition
Normal probability paper is constructed by connecting the standard normal distribution. It is a rectangular coordinate system. The horizontal axis scale is evenly ticked, indicating the observed value; the vertical axis is uneven, indicating the function value of the standard normal distribution. See Figure 1. The method of drawing normal probability paper is shown in Appendix A (Supplement). 3 Application steps
3.1 Steps
Collect observations. wwW.bzxz.Net
Organize the data. According to the size of the observations, list them from small to large, and summarize the frequency, cumulative frequency and cumulative frequency of each observation channel. When n230:
Cumulative frequency:
Cumulative frequency =
Cumulative frequency - median rank
[Press 1 and check the median rank table, see Appendix B (Supplement) Dot on the normal probability paper, the horizontal axis value is the observed value, and the vertical axis value is the corresponding cumulative rate value. Draw a straight line so that the number of points on both sides of the line is roughly equal, and the mean deviation of each point from the line is as small as possible. d. Infer whether the observed value comes from a normally distributed population. If the deviation of each point from the straight line is not large (especially the point with a vertical coordinate of 50), it can be inferred that the population follows a normal distribution + and the following steps can be performed. e. Estimate the mean and standard deviation of the population. The horizontal coordinate value corresponding to the point with a vertical coordinate of 50 on the straight line is: The horizontal coordinate value corresponding to the point with a vertical coordinate of 0.135 on the straight line is 1/3 of the difference (taken as the absolute value) between the product and the output. f. Estimate the defective rate P of the population. If the observed value is a quality characteristic value with specification requirements, the estimated value of the defective rate of the population is the interval length of the vertical coordinate corresponding to the interval where the unqualified observed value on the horizontal coordinate is located. Note, when there are many observations, the observations can be grouped and the above steps can be performed. Approved by the Ministry of Machinery Industry on December 9, 1994
Implemented on October 1, 1995
JB/T 3736. 4-94
Figure 1 Normal probability paper
3.2 Example
JB/T 3736. + -94
The dimension requirement of a certain part is 10:%. The dimensions of 48 parts of this kind are shown in Table 1. Table
10-050
Arrange the data, see Table 2.
Observed value
10,049
Put points on the normal probability paper and draw a straight line, see Figure 2. Table 2
Cumulative frequency
Observing the points and the straight line in Figure 2, it can be inferred that the observed values ​​come from a normally distributed population. mrn
Cumulative rate
As shown in Figure 2, the mean value = 10.0499 mm, the point with a vertical coordinate value of 0.135 corresponds to a horizontal coordinate value of 10.0444, so 10.0499-10.04440.0018 (mm).
As shown in Figure 2, the tolerance range is 0.045-0.055, and the part outside the interval is the unqualified area. The corresponding vertical coordinate interval length is the overall unqualified product rate 0 = 0.8%.
JB/T 3736. 4 -- 94
10.35116.05310.055
10.04510.Ca710.045
JB/T 3736. 4—94
Drawing of Normal Probability Paper
(Supplementary)
Normal probability paper is designed based on the principle that the measurement results of normal distribution can form a straight line on the drawing. Its horizontal axis is uniform, indicating the observed value, and the vertical axis is uneven, indicating the function value of normal distribution. The method for determining the ordinate value is as follows: select representative points α = 0.01%, 0.02%, 0.1%, 0.2%, 1%, 2%, 20%, 22%, 80%, 81%, ..., 99%, 99.1%, 99.9%, 99.91%, 99.9 ... Table A1 Quantile table of standard normal distribution
.- 1. 55
.-0.92
0, 84
— 0. 77
— 0. 64
— 0. 25
Appendix B
Median rank table (applicable to when the number of observations is less than 30) (supplement)
Median rank table
Additional notes:
This standard is proposed and coordinated by the Machinery Standardization Research Institute of the Ministry of Machinery Industry. 15
Continued Table B1
This standard was drafted by Beijing No. 1 Machine Tool Factory, Machinery Standardization Research Institute of the Ministry of Machinery Industry, Shenyang No. 3 Machine Tool Factory, and Shenyang Heavy Machinery Factory. The main drafters of this standard are Zhang Baosheng, Hongzhang, Wei Jing, Tian Jing, Xiao Quanxiang, Chu Ruji, 24
JB/T 3736. 4 94
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