Table 1. Summary of methods.

	WHO	Cullen	C-sum
Calculation	xn-1 Where,  x = the highest observed number of cases for a given month, over the course of several years	μ + 1.036*σX Where,  μ = the mean number of cases for a given month  σ = the standard deviation of cases for a given month	xn/((in-1 + in + in+1)/I) Where,  x = the number of cases for a given month for the current year  i = the number of cases for a given month for past years  I = the number of months considered (i.e., 3 months)
Complexity of calculation	Easy	Medium	Difficult
Resources required for calculation	Could be computed by hand	Log-transformation much easier with statistical software or spreadsheet	Log-transformation and moving window much easier with statistical software or spreadsheet
Sensitivity	Moderately sensitive	Least sensitive	Most sensitive
Best application	Resource-constrained settings Small datasets Rare disease	Larger datasets (>30 observations/time unit) Non-rare endemic disease	Larger datasets (>30 observations/time unit) Datasets with temporal stochasticity

Each of the three thresholds are evaluated on the basis of ease or complexity of calculation, resources required for calculation, and sensitivity.