Conventional statistics and robust statistics for proficiency testing in laboratory medicine

doi:10.3969/j.issn.1673-8640.2017.05.020

Abstract

Abstract:

Objective To investigate the scopes of conventional statistics（x and s after removal of outliers by Dixon method） and robust statistics [median and normalized interquartile range（NIQR）] for proficiency testing in laboratory medicine. Methodse Participants of the Proficiency Testing Program 2016 on C-reactive protein organized by Shanghai Center for Clinical Laboratory were classified into group A（29 laboratories）,group B（15 laboratories）and group C（9 laboratories）according to determination systems. The results of conventional statistics and robust statistics were analyzed and compared. Results As for group A,the designated values were same for the 2 methods. However,the NIQR and standard uncertainty （u_x）of designated values by conventional statistics were smaller than s and u_x by robust statistics. As for group B,the designated values were close between the 2 methods. Conventional statistics had u_x<0.3σ,and robust method had u_x>0.3σ. As for group C,the designated values were close between the 2 methods. Both methods had u_x>0.3σ. The s of conventional statistics was smaller than the NIQR of robust statistics. Conclusions When the number of participants is >18,robust statistics can be used. When the number of participants is 12-18,conventional statistics may be used. When the number is ≤12,besides conventional statistics should be used,the u_x of designated values should be considered as well.

Key words: Statistical methods, Clinical laboratories, Proficiency testing, Robust statistics, Conventional statistics, Dixon method, Uncertainty

CLC Number:

R446.1

GUO Xiaojun, ZHU Lingfeng, XU Chong, JU Yi. Conventional statistics and robust statistics for proficiency testing in laboratory medicine[J]. Laboratory Medicine, 2017, 32(5): 435-439.

Figures/Tables 6

References 9

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编号	样本1	样本2	样本3	样本4	样本5
1	27.19	27.33	14.98	48.35	34.49
2	28.20	27.50	15.20	47.70	34.60
3	28.01	27.38	15.69	47.63	34.99
4	28.20	28.60	15.40	48.60	35.60
5	27.21	29.36	15.12	47.52	35.22
6	27.50	26.32	12.63*	42.19^*	34.96
7	27.48	29.11	15.92	46.87	34.53
8	28.53	27.98	15.80	48.81	35.33
9	25.30	28.30	15.30	49.00^*	32.70
10	28.00	27.33	15.25	47.39	34.39
11	27.35	26.01	16.76	52.54^*	35.54
12	26.87	26.26	15.22	48.83	36.51
13	26.19	28.86	16.85	50.90	35.04
14	29.45	27.50	15.91	52.62^*	33.39
15	28.09	28.38	15.29	48.17	35.28
16	28.50	28.64	16.02	49.04	36.20
17	29.02	28.61	15.81	48.9	35.36
18	27.10	28.02	14.98	47.11	34.25
19	26.50	26.40	15.10	45.80	34.80
20	29.29	29.74	16.03	48.67	35.48
21	29.10	27.84	15.60	48.30	35.51
22	30.76	27.53	17.54^*	53.91^*	35.85
23	27.59	27.24	15.35	47.27	35.69
24	27.75	28.24	16.23	50.68	35.76
25	30.64	26.99	17.26	48.98	36.92
26	27.49	24.29^*	15.00	44.72^*	32.67^*
27	29.36	28.27	15.60	48.49	35.51
28	24.14	21.87^**	13.41^*	40.21^**	30.60^*
29	31.05	29.88	17.18	51.26	36.68

编号	样本1	样本2	样本3	样本4	样本5
1	27.19	27.33	14.98	48.35	34.49
2	28.20	27.50	15.20	47.70	34.60
3	28.01	27.38	15.69	47.63	34.99
4	28.20	28.60	15.40	48.60	35.60
5	27.21	29.36	15.12	47.52	35.22
6	27.50	26.32	12.63*	42.19^*	34.96
7	27.48	29.11	15.92	46.87	34.53
8	28.53	27.98	15.80	48.81	35.33
9	25.30	28.30	15.30	49.00^*	32.70
10	28.00	27.33	15.25	47.39	34.39
11	27.35	26.01	16.76	52.54^*	35.54
12	26.87	26.26	15.22	48.83	36.51
13	26.19	28.86	16.85	50.90	35.04
14	29.45	27.50	15.91	52.62^*	33.39
15	28.09	28.38	15.29	48.17	35.28
16	28.50	28.64	16.02	49.04	36.20
17	29.02	28.61	15.81	48.9	35.36
18	27.10	28.02	14.98	47.11	34.25
19	26.50	26.40	15.10	45.80	34.80
20	29.29	29.74	16.03	48.67	35.48
21	29.10	27.84	15.60	48.30	35.51
22	30.76	27.53	17.54^*	53.91^*	35.85
23	27.59	27.24	15.35	47.27	35.69
24	27.75	28.24	16.23	50.68	35.76
25	30.64	26.99	17.26	48.98	36.92
26	27.49	24.29^*	15.00	44.72^*	32.67^*
27	29.36	28.27	15.60	48.49	35.51
28	24.14	21.87^**	13.41^*	40.21^**	30.60^*
29	31.05	29.88	17.18	51.26	36.68

方法	统计量	样本1	样本2	样本3	样本4	样本5
传统统计法		28.00	27.58	15.60	48.29	34.96
	s	1.52	1.63	1.02	2.81	1.31
	CV（%）	5.44	5.90	6.51	5.81	3.75
	u_x	0.28	0.30	0.19	0.52	0.24
	0.3σ	0.46	0.49	0.31	0.84	0.39
稳健统计法	med	28.00	27.84	15.60	48.49	35.28
	NIQR	1.38	1.10	0.64	1.25	0.84
	RCV（%）	4.93	3.95	4.10	2.58	2.38
	u_x	1.38	1.10	0.64	1.25	0.84
	0.3σ	0.41	0.33	0.19	0.38	0.25

方法	统计量	样本1	样本2	样本3	样本4	样本5
传统统计法		28.00	27.58	15.60	48.29	34.96
	s	1.52	1.63	1.02	2.81	1.31
	CV（%）	5.44	5.90	6.51	5.81	3.75
	u_x	0.28	0.30	0.19	0.52	0.24
	0.3σ	0.46	0.49	0.31	0.84	0.39
稳健统计法	med	28.00	27.84	15.60	48.49	35.28
	NIQR	1.38	1.10	0.64	1.25	0.84
	RCV（%）	4.93	3.95	4.10	2.58	2.38
	u_x	1.38	1.10	0.64	1.25	0.84
	0.3σ	0.41	0.33	0.19	0.38	0.25

编号	样本1	样本2	样本3	样本4	样本5
1	30.70	28.80	17.40	56.60	37.40
2	33.80	31.30	21.60^*△	53.30	36.30
3	31.80	27.90	18.70	49.10	35.60
4	31.00	28.90	18.70	48.80	34.70
5	30.50	29.10	18.10	48.50	35.90
6	32.10	29.80	19.40	51.10	36.10
7	31.60	28.40	19.00	50.20	35.80
8	30.30	27.80	18.40	45.80	33.60
9	31.20	27.90	18.10	49.50	35.20
10	31.40	28.00	18.20	49.80	35.30
11	31.80	28.20	18.60	50.40	35.60
12	31.60	28.50	18.50	50.10	35.30
13	33.50	30.10	19.30	53.10	37.00
14	30.13	28.05	17.81	48.17	35.10
15	42.69^*△	45.32^*△	32.1^*△	63.47^*△	69.41^*△