前面所介绍的描述性指标:均数、标数差与方差;确定医学正值范围的正态分布法以及t 检验、u检验、方差分析等的应用条件是要求资料来自正态分布或近似正态分布。因此,在应用以上指标或分析方法时常要进行正态性检验,以判断资料是否属于正态分布。这里仅介绍正态概率纸目测法。
正态概率纸目测法是一种较粗略而简便的正态性检验方法。本法先要计算累计频数和累计频率,然的将累计频率点在正态概率纸上,若散点基本在一直线上,便可认为此资料服从正态分布;若散点偏离直线过远,可怀疑此资料不服从正态分布。
表19-15 110名20岁健康男大学生身高(cm)正态性检验计算表
身高组段(1) | 频数(2) | 累计频数*(3) | 累计频率(%)(4) | 概率单位(5) |
162~ | 1 | 1 | 0.9 | 2.63 |
164~ | 4 | 5 | 4.5 | 3.30 |
166~ | 9 | 14 | 12.7 | 3.86 |
168~ | 13 | 27 | 24.5 | 4.31 |
170~ | 19 | 46 | 41.8 | 4.79 |
172~ | 27 | 73 | 66.4 | 5.42 |
174~ | 16 | 89 | 80.9 | 5.87 |
176~ | 8 | 97 | 88.2 | 6.19 |
178~ | 8 | 105 | 95.5 | 6.70 |
180~ | 3 | 108 | 98.2 | 7.10 |
182~184 | 2 | 110 | 100.0 | — |
*表中第(3)栏是第(2)栏的频数累计数;第(4)栏是第(3)栏的各数值除以110所得的百分率
例19.12 判断表18-1110名20岁健康男大学生身高的资料是否服从正态分布。
在正态概率纸上,第(1)栏各组段的上限为横坐标,以第(4)栏相应的累计频率为纵坐标描点,如图19-4。注意:各组段的累计频率应标在横轴相应组段的上限位置上(即下一组段的下限),累计频率100%不能在图中标出。图19-4中散点基本在一直线上,故可认为该地20岁健康男大学生的身高服从正态分布。
如果没有正态概率纸,则可根据各组段累计频率,从附表19-4百分率与概率单位对照表上查出表19-15第(5)栏(即累计频率单位),然后把第(1)、(5)栏数据标在方格坐标纸上,所得散点图(图19-5)与图19-4一致。
图19-4 表18-1资料用正态概率纸 图19-5 表18-2资料用概率单位作图
作正态性检验 行正态性检验
附表19-1 t值表
ν | P(双侧)0.05 | 0.01 | 0.001 | ν | 0.05 | 0.01 | 0.001 |
P(单侧)0.025 | 0.005 | 0.0005 | 0.025 | 0.005 | 0.0005 | ||
1 | 12.706 | 63.657 | 636.618 | 21 | 2.080 | 2.831 | 3.819 |
2 | 4.303 | 9.925 | 31.598 | 22 | 2.072 | 2.819 | 3.792 |
3 | 3.182 | 5.841 | 12.924 | 23 | 2.069 | 2.807 | 3.767 |
4 | 2.776 | 4.604 | 8.610 | 24 | 2.064 | 2.797 | 3.745 |
5 | 2.571 | 4.032 | 6.859 | 25 | 2.060 | 2.787 | 3.725 |
6 | 2.447 | 3.707 | 5.959 | 26 | 2.056 | 2.779 | 3.707 |
7 | 2.365 | 3.499 | 5.405 | 27 | 2.052 | 2.771 | 3.690 |
8 | 2.306 | 3.355 | 5.041 | 28 | 2.048 | 2.763 | 3.674 |
9 | 2.262 | 3.250 | 4.781 | 29 | 2.045 | 2.756 | 3.659 |
10 | 2.228 | 3.169 | 4.587 | 30 | 2.042 | 2.750 | 3.646 |
11 | 2.201 | 3.106 | 4.437 | 40 | 2.021 | 2.704 | 3.551 |
12 | 2.179 | 3.055 | 4.318 | 50 | 2.008 | 2.678 | 3.496 |
13 | 2.160 | 3.012 | 4.221 | 60 | 2.000 | 2.660 | 3.460 |
14 | 2.145 | 2.977 | 4.140 | 70 | 1.994 | 2.648 | 3.435 |
15 | 2.131 | 2.947 | 4.073 | 80 | 1.989 | 2.638 | 3.416 |
16 | 2.120 | 2.921 | 4.015 | 90 | 1.986 | 2.631 | 3.402 |
17 | 2.110 | 2.898 | 3.965 | 100 | 1.982 | 2.625 | 3.390 |
18 | 2.101 | 2.878 | 3.922 | 120 | 1.980 | 2.617 | 3.373 |
19 | 2.093 | 2.861 | 3.883 | 500 | 1.965 | 2.586 | 3.305 |
20 | 2.086 | 2.845 | 3.850 | ∞ | 1.960 | 2.576 | 3.291 |
附表19-2 F界值表(方差分析用,上行:P=0.05,P=0.01)
V2(较小均方的自由度) |
V1(较大均方的自由度) | ||||||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 12 | 24 | ∞ | |
1 | 161.4 | 199.5 | 215.7 | 224.6 | 230.2 | 234.0 | 236.8 | 238.9 | 243.9 | 249.1 | 254.3 |
4052 | 4999.5 | 5403 | 5625 | 5764 | 5859 | 5928 | 5982 | 6106 | 6235 | 6366 | |
2 | 18.51 | 19.00 | 19.16 | 19.25 | 19.30 | 19.33 | 19.35 | 19.37 | 19.41 | 19.45 | 19.50 |
98.50 | 99.00 | 99.17 | 99.25 | 99.30 | 99.33 | 99.36 | 99.37 | 99.42 | 99.46 | 99.50 | |
3 | 10.13 | 9.55 | 9.28 | 9.12 | 9.01 | 8.94 | 8.89 | 8.85 | 8.74 | 8.64 | 8.53 |
34.12 | 30.82 | 29.46 | 28.17 | 28.24 | 27.91 | 27.67 | 27.49 | 27.05 | 26.60 | 26.13 | |
4 | 7.71 | 6.94 | 6.59 | 6.39 | 6.26 | 6.16 | 6.09 | 6.04 | 5.91 | 5.77 | 5.63 |
21.20 | 18.00 | 16.69 | 15.98 | 15.52 | 15.21 | 14.98 | 14.80 | 14.37 | 13.93 | 13.46 | |
5 | 6.61 | 5.79 | 5.41 | 5.19 | 5.05 | 4.95 | 4.88 | 4.82 | 4.68 | 4.53 | 4.36 |
16.26 | 13.27 | 12.06 | 11.39 | 10.97 | 10.67 | 10.46 | 10.29 | 9.89 | 9.47 | 9.02 | |
6 | 5.99 | 5.14 | 4.76 | 4.53 | 4.39 | 4.28 | 4.21 | 4.15 | 4.00 | 3.84 | 3.67 |
13.75 | 10.92 | 9.78 | 9.15 | 8.75 | 8.47 | 8.26 | 8.10 | 7.72 | 7.31 | 6.88 | |
7 | 5.59 | 4.74 | 4.35 | 4.12 | 3.97 | 3.87 | 3.79 | 3.73 | 3.57 | 3.41 | 3.23 |
12.25 | 9.55 | 8.45 | 7.85 | 7.46 | 7.19 | 6.99 | 6.84 | 6.47 | 6.07 | 5.65 | |
8 | 5.32 | 4.46 | 4.07 | 3.84 | 3.69 | 3.58 | 3.50 | 3.44 | 3.28 | 3.12 | 2.93 |
11.26 | 8.65 | 7.59 | 7.01 | 6.63 | 6.37 | 6.18 | 6.03 | 5.67 | 5.28 | 4.86 | |
9 | 5.12 | 4.26 | 3.86 | 3.63 | 3.48 | 3.37 | 3.29 | 3.23 | 3.07 | 2.90 | 2.71 |
10.56 | 8.02 | 6.99 | 6.42 | 6.06 | 5.80 | 5.61 | 5.47 | 5.11 | 4.73 | 4.31 | |
10 | 4.96 | 4.10 | 3.71 | 3.48 | 3.33 | 3.22 | 3.14 | 3.07 | 2.91 | 2.74 | 2.54 |
10.04 | 7.56 | 6.55 | 5.99 | 5.64 | 5.39 | 5.20 | 5.06 | 4.71 | 4.33 | 3.91 | |
12 | 4.75 | 3.89 | 3.49 | 3.26 | 3.11 | 3.00 | 2.91 | 2.85 | 2.69 | 2.51 | 2.30 |
9.33 | 6.93 | 5.95 | 5.41 | 5.06 | 4.82 | 4.64 | 4.50 | 4.16 | 3.78 | 3.36 | |
14 | 4.60 | 3.74 | 3.34 | 3.11 | 2.96 | 2.85 | 2.76 | 2.70 | 2.53 | 2.35 | 2.13 |
8.86 | 6.51 | 5.56 | 5.04 | 4.69 | 4.46 | 4.28 | 4.14 | 3.80 | 3.43 | 3.00 | |
16 | 4.49 | 3.63 | 3.24 | 3.01 | 2.85 | 2.74 | 2.66 | 2.59 | 2.42 | 2.24 | 2.01 |
8.53 | 6.23 | 5.29 | 4.77 | 4.44 | 4.20 | 4.03 | 3.89 | 3.55 | 3.18 | 2.75 | |
18 | 4.41 | 3.55 | 3.16 | 2.93 | 2.77 | 2.66 | 2.58 | 2.51 | 2.34 | 2.15 | 1.92 |
8.29 | 6.01 | 5.09 | 4.58 | 4.25 | 4.01 | 3.84 | 3.71 | 3.37 | 3.00 | 2.57 | |
20 | 4.35 | 3.49 | 3.10 | 2.87 | 2.71 | 2.60 | 2.51 | 2.45 | 2.28 | 2.08 | 1.84 |
8.10 | 5.85 | 4.94 | 4.43 | 4.10 | 3.87 | 3.70 | 3.56 | 3.23 | 2.86 | 2.42 | |
30 | 4.17 | 3.32 | 2.92 | 2.69 | 2.53 | 2.42 | 2.33 | 2.27 | 2.09 | 1.89 | 1.62 |
7.56 | 5.39 | 4.51 | 4.02 | 3.70 | 3.47 | 3.30 | 3.17 | 2.84 | 2.47 | 2.01 | |
40 | 4.08 | 3.23 | 2.84 | 2.61 | 2.45 | 2.34 | 2.25 | 2.18 | 2.00 | 1.79 | 1.51 |
7.31 | 5.18 | 4.31 | 3.83 | 3.51 | 3.29 | 3.12 | 2.99 | 2.66 | 2.29 | 1.80 | |
60 | 4.00 | 3.15 | 2.76 | 2.53 | 2.37 | 2.25 | 2.17 | 2.10 | 1.92 | 1.70 | 1.39 |
7.08 | 4.98 | 4.13 | 3.65 | 3.34 | 3.12 | 2.95 | 2.82 | 2.50 | 2.12 | 1.60 | |
120 | 3.92 | 3.07 | 2.68 | 2.45 | 2.29 | 2.17 | 2.09 | 2.02 | 1.83 | 1.61 | 1.25 |
6.85 | 4.79 | 3.95 | 3.48 | 3.17 | 2.96 | 2.79 | 2.66 | 2.34 | 1.95 | 1.38 | |
∞ | 3.84 | 3.00 | 2.60 | 2.37 | 2.21 | 2.10 | 2.01 | 1.94 | 1.75 | 1.52 | 1.00 |
6.63 | 4.61 | 3.78 | 3.32 | 3.02 | 2.80 | 2.64 | 2.51 | 2.18 | 1.79 | 1.00 |
附表19-3 Newman-Keuls检验用q界值表
(上行:P=0.05,下行:P=0.01)
V |
组 数,a | ||||||||
2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | |
5 | 3.64 | 4.60 | 5.22 | 5.67 | 6.03 | 6.33 | 6.58 | 6.80 | 6.99 |
5.70 | 6.98 | 7.80 | 8.42 | 8.91 | 9.32 | 9.67 | 9.97 | 10.24 | |
6 | 3.46 | 4.34 | 4.90 | 5.30 | 5.63 | 5.90 | 6.12 | 6.32 | 6.49 |
5.24 | 6.33 | 7.03 | 7.56 | 7.97 | 8.32 | 8.61 | 8.87 | 9.10 | |
7 | 3.34 | 4.16 | 4.68 | 5.06 | 5.36 | 5.61 | 5.82 | 6.00 | 6.16 |
4.95 | 5.92 | 6.54 | 7.01 | 7.37 | 7.68 | 7.94 | 8.17 | 8.37 | |
8 | 3.26 | 4.04 | 4.53 | 4.89 | 5.17 | 5.40 | 5.60 | 5.77 | 5.92 |
4.75 | 5.64 | 6.20 | 6.62 | 6.96 | 7.24 | 7.47 | 7.68 | 7.86 | |
9 | 3.20 | 3.95 | 4.41 | 4.76 | 5.02 | 5.24 | 5.43 | 5.59 | 5.74 |
4.60 | 5.43 | 5.96 | 6.35 | 6.66 | 6.91 | 7.13 | 7.33 | 7.49 | |
10 | 3.15 | 3.88 | 4.33 | 4.65 | 4.91 | 5.12 | 5.30 | 5.46 | 5.60 |
4.48 | 5.27 | 5.77 | 6.14 | 6.43 | 6.67 | 6.87 | 7.05 | 7.21 | |
12 | 3.08 | 3.77 | 4.20 | 4.51 | 4.75 | 4.95 | 5.12 | 5.27 | 5.39 |
4.32 | 5.05 | 5.50 | 5.84 | 6.10 | 6.32 | 6.51 | 6.67 | 6.81 | |
14 | 3.03 | 3.70 | 4.11 | 4.41 | 4.64 | 4.83 | 4.99 | 5.13 | 5.25 |
4.21 | 4.89 | 5.32 | 5.63 | 5.88 | 6.08 | 6.26 | 6.41 | 6.54 | |
16 | 3.00 | 3.65 | 4.05 | 4.33 | 4.56 | 4.74 | 4.90 | 5.03 | 5.15 |
4.13 | 4.79 | 5.19 | 5.49 | 5.72 | 5.92 | 6.08 | 6.22 | 6.35 | |
18 | 2.97 | 3.61 | 4.00 | 4.28 | 4.49 | 4.67 | 4.82 | 4.96 | 5.07 |
4.07 | 4.70 | 5.09 | 5.38 | 5.60 | 5.79 | 5.94 | 6.08 | 6.20 | |
20 | 2.95 | 3.58 | 3.96 | 4.23 | 4.45 | 4.62 | 4.77 | 4.90 | 5.01 |
4.02 | 4.64 | 5.02 | 5.29 | 5.51 | 5.69 | 5.84 | 5.97 | 6.09 | |
30 | 2.89 | 3.49 | 3.85 | 4.10 | 4.30 | 4.46 | 4.60 | 4.72 | 4.82 |
3.89 | 4.45 | 4.80 | 5.05 | 5.24 | 5.40 | 5.04 | 5.65 | 5.76 | |
40 | 2.86 | 3.44 | 3.79 | 4.04 | 4.23 | 4.39 | 4.52 | 4.63 | 4.73 |
3.82 | 4.37 | 4.70 | 4.93 | 5.11 | 5.26 | 5.39 | 5.50 | 5.60 | |
60 | 2.83 | 3.40 | 3.74 | 3.98 | 4.16 | 4.31 | 4.44 | 4.55 | 4.65 |
3.76 | 4.28 | 4.59 | 4.82 | 4.99 | 5.13 | 5.25 | 5.36 | 5.45 | |
120 | 2.80 | 3.36 | 3.68 | 3.92 | 4.10 | 4.24 | 4.36 | 4.47 | 4.56 |
3.70 | 4.20 | 4.50 | 4.71 | 4.87 | 5.01 | 5.12 | 5.21 | 5.30 | |
∞ | 2.77 | 3.31 | 3.63 | 3.86 | 4.03 | 4.17 | 4.29 | 4.39 | 4.47 |
3.64 | 4.12 | 4.40 | 4.60 | 4.76 | 4.88 | 4.99 | 5.08 | 5.16 |
附表19-4 百分率与概率单位对照表
百分率 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
0 | — | 2.67 | 2.95 | 3.12 | 3.25 | 3.36 | 3.45 | 3.52 | 3.59 | 3.66 |
10 | 3.72 | 3.77 | 3.83 | 3.87 | 3.92 | 3.96 | 4.01 | 4.05 | 4.08 | 4.12 |
20 | 4.16 | 4.19 | 4.23 | 4.26 | 4.29 | 4.33 | 4.36 | 4.39 | 4.42 | 4.45 |
30 | 4.48 | 4.50 | 4.53 | 4.56 | 4.59 | 4.61 | 4.64 | 4.67 | 4.69 | 4.72 |
40 | 4.75 | 4.77 | 4.80 | 4.82 | 4.85 | 4.87 | 4.90 | 4.92 | 4.95 | 4.97 |
50 | 5.00 | 5.03 | 5.05 | 5.08 | 5.10 | 5.13 | 5.15 | 5.18 | 5.20 | 5.23 |
60 | 5.25 | 5.28 | 5.31 | 5.33 | 5.36 | 5.39 | 5.41 | 5.44 | 5.47 | 5.50 |
70 | 5.52 | 5.55 | 5.58 | 5.61 | 5.64 | 5.67 | 5.71 | 5.74 | 5.77 | 5.81 |
80 | 5.84 | 5.88 | 5.92 | 5.95 | 5.99 | 6.04 | 6.08 | 6.13 | 6.18 | 6.23 |
90 | 6.28 | 6.34 | 6.41 | 6.48 | 6.55 | 6.64 | 6.75 | 6.88 | 7.05 | 7.33 |
90以上百分率 | 0.0 | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 |
99 | 7.33 | 7.37 | 7.41 | 7.46 | 7.51 | 7.58 | 7.65 | 7.75 | 7.88 | 8.09 |