Table 5.

Analysis of the criteria for the classification of colorectal tumors in the RER− subtypes

Tested loci, n						Minimum FUM requested for classification of a tumor as not belonging to RER− subtype*
	Probability of observation of RER at dinucleotide repeat loci in RER− tumors					Risk of misclassification =
	None	1	2	1 or 2	≥3	P < 0.05	P < 0.01	P < 0.001
2	0.960	0.039	0.000	0.040	—	0.50	—	—
	0.967	0.033	0.000	0.033		0.50
3	0.941	0.058	0.001	0.059	0.000	0.66	0.66	—
	0.943	0.056	0.000	0.057	0.000	0.66	0.66	0.66
4	0.922	0.075	0.002	0.078	0.000	0.50	0.50	0.75
	0.933	0.065	0.002	0.067	0.000	0.50	0.05	0.75
8	0.851	0.139	0.010	0.149	0.000	0.25	0.25	0.38
	0.87	0.122	0.009	0.131	0.000	0.25	0.25	0.38
12	0.785	0.192	0.022	0.214	0.002	0.17	0.25	0.33
	0.806	0.175	0.017	0.192	0.001	0.17	0.25	0.33
16	0.724	0.236	0.036	0.273	0.004	0.13	0.19	0.25
	0.758	0.208	0.030	0.238	0.003	0.13	0.19	0.25
20	0.668	0.272	0.053	0.325	0.007	0.15	0.15	0.20
	0.700	0.247	0.048	0.295	0.005	0.10	0.15	0.20

The data were obtained either from a binomial distribution, assuming that the probability for any locus to exhibit replication error in a RER− tumor is equal to 0.02 (numbers in roman type) or, to derive probabilities that are independent of the assumption of Poisson distribution, from simulations that were performed by choosing randomly tumors and loci within the set of data obtained on the RER− tumors. Each line corresponds to 5,000 trials (numbers in italic type). 

^*Because the FUM is the ratio of two integers, occasionally, the minimum FUM to avoid misclassification does not decrease regularly as the number of tested loci increases.