How to spot bias and other potential problems in randomised controlled trials

S C Lewis; C P Warlow

doi:10.1136/jnnp.2003.025833

Article metrics

Review: neuroscience for neurologists

How to spot bias and other potential problems in randomised controlled trials

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Online download statistics by month: January 2004 to October 2024

	Abstract	Full	Pdf
Jan 2004	0	364	200
Feb 2004	0	401	196
Mar 2004	1	196	106
Apr 2004	0	109	58
May 2004	1	59	34
Jun 2004	0	67	32
Jul 2004	0	116	33
Aug 2004	0	135	34
Sep 2004	0	101	29
Oct 2004	13	49	28
Nov 2004	20	92	22
Dec 2004	17	65	29
Jan 2005	26	92	19
Feb 2005	14	59	69
Mar 2005	20	107	68
Apr 2005	12	107	82
May 2005	17	101	83
Jun 2005	9	50	47
Jul 2005	3	54	49
Aug 2005	14	52	45
Sep 2005	8	47	49
Oct 2005	10	92	63
Nov 2005	12	72	65
Dec 2005	9	51	37
Jan 2006	3	68	47
Feb 2006	9	51	40
Mar 2006	4	77	54
Apr 2006	7	119	53
May 2006	10	84	45
Jun 2006	7	49	36
Jul 2006	2	50	17
Aug 2006	4	76	26
Sep 2006	5	66	31
Oct 2006	7	101	52
Nov 2006	2	128	54
Dec 2006	2	70	29
Jan 2007	20	91	37
Feb 2007	6	75	27
Mar 2007	3	88	45
Apr 2007	48	21	16
May 2007	71	44	33
Jun 2007	34	28	20
Jul 2007	36	34	21
Aug 2007	27	19	18
Sep 2007	35	17	16
Oct 2007	29	16	25
Nov 2007	25	53	38
Dec 2007	13	26	20
Jan 2008	23	37	13
Feb 2008	30	18	13
Mar 2008	21	42	23
Apr 2008	28	59	37
May 2008	25	22	15
Jun 2008	12	9	8
Jul 2008	13	27	6
Aug 2008	21	18	9
Sep 2008	46	33	18
Oct 2008	19	13	12
Nov 2008	18	9	11
Dec 2008	17	11	11
Jan 2009	29	23	12
Feb 2009	28	12	9
Mar 2009	38	31	22
Apr 2009	17	39	27
May 2009	26	23	16
Jun 2009	20	11	4
Jul 2009	23	12	11
Aug 2009	14	12	9
Sep 2009	12	22	19
Oct 2009	13	9	6
Nov 2009	30	45	21
Dec 2009	56	20	16
Jan 2010	15	10	6
Feb 2010	19	10	3
Mar 2010	31	20	18
Apr 2010	30	26	20
May 2010	24	20	12
Jun 2010	14	13	9
Jul 2010	28	14	13
Aug 2010	12	9	6
Sep 2010	30	11	10
Oct 2010	20	15	6
Nov 2010	34	26	23
Dec 2010	38	23	22
Jan 2011	22	22	62
Feb 2011	24	22	16
Mar 2011	59	46	19
Apr 2011	38	48	27
May 2011	52	22	22
Jun 2011	28	2	11
Jul 2011	29	13	8
Aug 2011	58	3	6
Sep 2011	32	6	5
Oct 2011	44	6	4
Nov 2011	34	38	31
Dec 2011	21	30	18
Jan 2012	13	33	12
Feb 2012	16	32	16
Mar 2012	10	47	24
Apr 2012	22	77	29
May 2012	16	58	20
Jun 2012	19	82	28
Jul 2012	15	54	29
Aug 2012	16	42	12
Sep 2012	18	86	35
Oct 2012	19	113	34
Nov 2012	0	166	35
Dec 2012	0	124	28
Jan 2013	0	181	39
Feb 2013	0	253	56
Mar 2013	0	282	44
Apr 2013	0	323	47
May 2013	0	397	71
Jun 2013	22	132	31
Jul 2013	9	135	21
Aug 2013	12	120	28
Sep 2013	12	143	19
Oct 2013	14	267	32
Nov 2013	19	345	54
Dec 2013	14	270	41
Jan 2014	25	295	64
Feb 2014	17	358	62
Mar 2014	38	419	57
Apr 2014	26	569	77
May 2014	34	476	81
Jun 2014	21	225	34
Jul 2014	26	363	31
Aug 2014	11	187	32
Sep 2014	18	365	50
Oct 2014	32	217	49
Nov 2014	45	153	51
Dec 2014	17	105	14
Jan 2015	24	197	19
Feb 2015	19	105	23
Mar 2015	16	335	45
Apr 2015	32	343	65
May 2015	28	401	37
Jun 2015	18	209	38
Jul 2015	16	169	17
Aug 2015	13	248	26
Sep 2015	22	285	26
Oct 2015	20	214	35
Nov 2015	43	342	50
Dec 2015	13	173	18
Jan 2016	27	317	45
Feb 2016	22	337	41
Mar 2016	19	370	53
Apr 2016	40	625	85
May 2016	38	485	77
Jun 2016	20	276	23
Jul 2016	15	194	39
Aug 2016	24	240	31
Sep 2016	23	264	42
Oct 2016	73	416	156
Nov 2016	44	416	78
Dec 2016	33	299	34
Jan 2017	39	395	144
Feb 2017	11	201	71
Mar 2017	5	323	65
Apr 2017	12	451	100
May 2017	15	537	138
Jun 2017	45	297	41
Jul 2017	76	75	15
Aug 2017	86	82	16
Sep 2017	363	357	54
Oct 2017	645	634	128
Nov 2017	612	580	85
Dec 2017	475	443	62
Jan 2018	476	458	62
Feb 2018	728	705	94
Mar 2018	624	596	70
Apr 2018	1030	1018	135
May 2018	675	674	61
Jun 2018	319	318	24
Jul 2018	337	337	41
Aug 2018	526	526	56
Sep 2018	546	544	100
Oct 2018	932	930	163
Nov 2018	1252	1238	164
Dec 2018	837	835	71
Jan 2019	913	906	108
Feb 2019	1005	1000	133
Mar 2019	1120	1106	138
Apr 2019	1281	1272	210
May 2019	1028	1011	142
Jun 2019	591	581	51
Jul 2019	466	460	44
Aug 2019	528	516	74
Sep 2019	555	549	60
Oct 2019	761	753	144
Nov 2019	1242	1210	181
Dec 2019	606	590	102
Jan 2020	543	525	85
Feb 2020	689	671	118
Mar 2020	790	780	133
Apr 2020	825	815	197
May 2020	640	626	118
Jun 2020	521	517	59
Jul 2020	585	573	86
Aug 2020	863	839	119
Sep 2020	886	872	80
Oct 2020	1205	1183	158
Nov 2020	1033	998	174
Dec 2020	727	713	121
Jan 2021	757	740	116
Feb 2021	995	982	114
Mar 2021	1093	1068	191
Apr 2021	990	985	166
May 2021	922	921	160
Jun 2021	420	429	75
Jul 2021	472	480	110
Aug 2021	453	466	98
Sep 2021	705	714	96
Oct 2021	1000	999	153
Nov 2021	702	683	137
Dec 2021	723	736	109
Jan 2022	910	912	157
Feb 2022	908	968	207
Mar 2022	1202	1274	248
Apr 2022	1320	1352	209
May 2022	1365	1419	260
Jun 2022	648	656	110
Jul 2022	481	499	100
Aug 2022	553	564	79
Sep 2022	726	724	69
Oct 2022	738	757	83
Nov 2022	863	858	91
Dec 2022	586	585	73
Jan 2023	687	695	127
Feb 2023	740	742	129
Mar 2023	938	905	135
Apr 2023	664	652	116
May 2023	718	694	134
Jun 2023	520	503	55
Jul 2023	771	769	102
Aug 2023	459	468	79
Sep 2023	505	511	50
Oct 2023	779	772	60
Nov 2023	780	642	89
Dec 2023	1234	165	39
Jan 2024	434	24	9
Feb 2024	457	54	19
Mar 2024	981	85	33
Apr 2024	931	54	52
May 2024	618	26	10
Jun 2024	415	15	3
Jul 2024	632	54	36
Aug 2024	411	27	13
Sep 2024	345	8	4
Oct 2024	431	23	10
Total	67199	79134	14802

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