Skip to main content
Subscribe
Log In
More
Log in via Institution
Log in via OpenAthens
Log in via RCEM
Log in using your username and password
For personal accounts OR managers of institutional accounts
Username
*
Password
*
Forgot your log in details?
Register a new account?
Forgot
your user name or password?
Basket
Search
More
Search for this keyword
Advanced search
Latest content
Current issue
Archive
Authors
About
Search for this keyword
Advanced search
Close
More
Main menu
Latest content
Current issue
Archive
Authors
About
Subscribe
Log in
More
Log in via Institution
Log in via OpenAthens
Log in via RCEM
Log in using your username and password
For personal accounts OR managers of institutional accounts
Username
*
Password
*
Forgot your log in details?
Register a new account?
Forgot
your user name or password?
BMJ Journals
You are here
Home
Archive
Volume 21, Issue 1
Correction
Email alerts
Article metrics
Article menu
Article
Text
Article
info
Citation
Tools
Share
Rapid Responses
Article
metrics
Alerts
See original article:
An introduction to power and sample size estimation - September 01, 2003
PDF
Correction
Correction
Free
Online download statistics by month:
Online download statistics by month: January 2004 to July 2022
Abstract
Full
Pdf
Jan 2004
0
16
4
Feb 2004
0
16
2
Mar 2004
0
6
0
Apr 2004
0
3
0
May 2004
0
8
0
Jun 2004
0
12
0
Jul 2004
0
26
1
Aug 2004
0
61
2
Sep 2004
0
63
0
Oct 2004
5
13
0
Nov 2004
6
15
2
Dec 2004
4
7
0
Jan 2005
4
20
4
Feb 2005
5
7
5
Mar 2005
3
14
1
Apr 2005
1
16
11
May 2005
1
10
5
Jun 2005
3
7
4
Jul 2005
1
10
3
Aug 2005
5
12
5
Sep 2005
0
8
4
Oct 2005
2
7
4
Nov 2005
0
4
1
Dec 2005
3
6
4
Jan 2006
1
12
5
Feb 2006
1
8
4
Mar 2006
1
7
4
Apr 2006
1
9
1
May 2006
0
7
3
Jun 2006
1
7
1
Jul 2006
0
6
6
Aug 2006
3
6
2
Sep 2006
1
5
4
Oct 2006
0
10
7
Nov 2006
0
5
4
Dec 2006
0
6
5
Jan 2007
0
6
3
Feb 2007
0
8
6
Mar 2007
0
8
4
Apr 2007
0
3
3
May 2007
1
9
4
Jun 2007
0
4
0
Jul 2007
2
8
3
Aug 2007
1
7
3
Sep 2007
0
4
1
Oct 2007
0
4
3
Nov 2007
2
5
3
Dec 2007
0
2
1
Jan 2008
1
11
6
Feb 2008
1
7
3
Mar 2008
2
2
1
Apr 2008
0
6
3
May 2008
0
2
1
Jun 2008
2
2
0
Jul 2008
2
1
1
Aug 2008
0
2
2
Sep 2008
1
3
2
Oct 2008
1
2
2
Nov 2008
1
2
2
Dec 2008
3
3
1
Jan 2009
1
4
3
Feb 2009
0
4
3
Mar 2009
0
4
3
Apr 2009
0
5
1
May 2009
0
3
1
Jun 2009
1
7
4
Jul 2009
1
12
4
Aug 2009
0
1
0
Sep 2009
0
1
1
Oct 2009
2
2
1
Nov 2009
2
4
2
Dec 2009
3
0
1
Jan 2010
1
42
9
Feb 2010
0
28
13
Mar 2010
0
16
2
Apr 2010
0
10
2
May 2010
4
2
3
Jun 2010
0
3
2
Jul 2010
0
4
2
Aug 2010
0
1
1
Sep 2010
6
7
0
Oct 2010
5
9
0
Nov 2010
2
3
1
Dec 2010
1
7
4
Jan 2011
1
2
0
Feb 2011
1
6
0
Mar 2011
6
5
1
Apr 2011
2
4
2
May 2011
7
3
3
Jun 2011
7
5
1
Jul 2011
11
5
3
Aug 2011
6
4
1
Sep 2011
5
16
5
Oct 2011
10
4
2
Nov 2011
25
10
2
Dec 2011
20
3
5
Jan 2012
9
6
4
Feb 2012
8
3
3
Mar 2012
16
6
8
Apr 2012
9
6
6
May 2012
11
8
8
Jun 2012
11
6
4
Jul 2012
20
8
6
Aug 2012
13
11
7
Sep 2012
17
7
7
Oct 2012
13
6
8
Nov 2012
0
6
10
Dec 2012
0
6
7
Jan 2013
0
21
9
Feb 2013
0
10
10
Mar 2013
0
11
7
Apr 2013
0
13
4
May 2013
0
12
11
Jun 2013
20
9
7
Jul 2013
13
10
5
Aug 2013
20
11
5
Sep 2013
15
9
11
Oct 2013
20
15
9
Nov 2013
13
6
3
Dec 2013
18
13
17
Jan 2014
21
6
7
Feb 2014
16
13
9
Mar 2014
26
20
9
Apr 2014
12
12
4
May 2014
20
13
7
Jun 2014
22
15
13
Jul 2014
24
12
10
Aug 2014
61
33
12
Sep 2014
60
35
15
Oct 2014
51
29
19
Nov 2014
62
35
20
Dec 2014
46
32
11
Jan 2015
67
40
19
Feb 2015
56
38
12
Mar 2015
68
37
15
Apr 2015
46
29
17
May 2015
64
42
14
Jun 2015
78
43
22
Jul 2015
69
47
20
Aug 2015
49
31
16
Sep 2015
53
37
21
Oct 2015
34
26
13
Nov 2015
66
49
20
Dec 2015
68
40
15
Jan 2016
63
40
17
Feb 2016
72
53
20
Mar 2016
72
49
14
Apr 2016
84
53
30
May 2016
94
69
29
Jun 2016
54
37
18
Jul 2016
61
31
19
Aug 2016
62
43
23
Sep 2016
57
37
21
Oct 2016
44
29
12
Nov 2016
117
82
33
Dec 2016
73
48
16
Jan 2017
89
58
17
Feb 2017
14
15
15
Mar 2017
0
37
25
Apr 2017
0
100
19
May 2017
0
76
6
Jun 2017
15
56
16
Jul 2017
15
15
6
Aug 2017
27
27
3
Sep 2017
61
61
5
Oct 2017
85
85
17
Nov 2017
84
84
8
Dec 2017
91
91
19
Jan 2018
110
110
13
Feb 2018
112
98
13
Mar 2018
114
112
15
Apr 2018
103
103
8
May 2018
120
120
14
Jun 2018
101
101
20
Jul 2018
125
125
25
Aug 2018
85
85
11
Sep 2018
89
89
22
Oct 2018
131
132
16
Nov 2018
123
123
17
Dec 2018
113
113
19
Jan 2019
139
138
18
Feb 2019
158
157
31
Mar 2019
143
143
20
Apr 2019
167
167
30
May 2019
157
157
24
Jun 2019
181
181
24
Jul 2019
147
146
25
Aug 2019
135
135
42
Sep 2019
153
153
34
Oct 2019
179
179
28
Nov 2019
215
214
38
Dec 2019
200
198
26
Jan 2020
283
282
62
Feb 2020
228
228
35
Mar 2020
244
243
36
Apr 2020
236
235
38
May 2020
231
231
51
Jun 2020
195
195
36
Jul 2020
173
173
28
Aug 2020
191
191
40
Sep 2020
224
224
49
Oct 2020
305
305
56
Nov 2020
294
294
46
Dec 2020
247
247
41
Jan 2021
287
287
44
Feb 2021
252
252
38
Mar 2021
135
134
23
Apr 2021
131
131
20
May 2021
146
146
22
Jun 2021
131
131
21
Jul 2021
122
122
24
Aug 2021
190
189
38
Sep 2021
239
239
51
Oct 2021
266
265
43
Nov 2021
288
284
51
Dec 2021
193
193
32
Jan 2022
250
250
38
Feb 2022
220
221
30
Mar 2022
266
266
33
Apr 2022
256
256
44
May 2022
243
242
37
Jun 2022
194
194
19
Jul 2022
181
181
26
Total
13062
13131
2863
Read the full text or download the PDF:
Subscribe
Log in
Log in via Institution
Log in via OpenAthens
Log in via RCEM
Log in using your username and password
For personal accounts OR managers of institutional accounts
Username
*
Password
*
Forgot your log in details?
Register a new account?
Forgot
your user name or password?
PDF