Misuse of Statistical Methods in 10 Leading Chinese Medical Journals in 1998 and 2008

Table 2

Statistical methods under different study designs.

Types of study design	1998		2008
	Articles that used statistical methods; 𝑛 (%)	Incorrect use of statistical methods; 𝑛 (%)	Articles that used statistical methods; 𝑛 (%)	Incorrect use of statistical methods; 𝑛 (%)
Systematic review	0	0	6 (100.0%)	0 (0%)
RCT*	64 (98.0%)	36 (56.3%)	56 (93.3%)	38 (67.9%)
Non-RCT**	82 (91.1%)	47 (57.3%)	58 (95.1%)	34 (58.6%)
Cohort study	47 (79.7%)	28 (59.6%)	80 (92.0%)	17 (21.3%)
Case-control study	254 (92.4%)	148 (58.3%)	276 (97.2%)	129 (46.7%)
Cross-sectional study	56 (74.7%)	32 (57.1%)	52 (88.1%)	23 (44.2%)
Case study or case series study	122 (31.9%)	59 (48.4%)	233 (48.9%)	110 (47.2%)
Diagnostic test	47 (74.6%)	20 (42.6%)	63 (82.9%)	25(39.7%)
Basic science study	240 (74.1%)	175 (72.9%)	409 (87.4%)	268 (65.5%)
Total	912 (68.3%)	545 (59.8%)	1233 (78.1%)	644 (52.2%)

*RCT: randomised controlled trial.
**Non-RCT: nonrandomised clinical trial.
𝑁 = total articles (1998:1335; 2008:1578).
All articles 𝑛 (%): n is the number of articles of each type of study design and percentage = n/N × 100%.
Articles that used statistical methods n (%): n is the number of articles using statistical methods in each type of study design and the percentage = n/the number of articles of each type of study design, incorrect use of statistical methods n (%): n is the number of articles using statistical methods incorrectly and percentage = n/the number of articles using statistical methods in each type of study design.