Table 2.

Summary of analysis results for 1000 simulated studies similar to those summarised in Table 1, but with intervention having no effect

Method	Per cent with P < 0.05*
Input fixed at 1,000,000 cells. Copies counted exactly.
A. 0 copies reset to 1, paired t-test	5.2
B. Add 1 to copies, paired t-test	5.5
C. 0 copies treated as left-censored	5.9
D. Negative binomial regression	3.9
Input fixed at 1,000,000 cells. Copies measured with error.
A. 0 copies reset to 1, paired t-test	5.4
B. Add 1 to copies, paired t-test	4.9
C. 0 copies treated as left-censored	5.8
D. Negative binomial regression	8.0
Input varies from 500,000 to 1,500,000 cells. Copies counted exactly.
A. 0 copies reset to 1, paired t-test	5.5
B. Add 1 to copies, paired t-test	5.0
C. 0 copies treated as left-censored	6.4
D. Negative binomial regression	4.8
Input varies from 500,000 to 1,500,000 cells. Copies measured with error.
A. 0 copies reset to 1, paired t-test	5.0
B. Add 1 to copies, paired t-test	5.9
C. 0 copies treated as left-censored	6.4
D. Negative binomial regression	7.3

*The ideal value for this is 5%.