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. Author manuscript; available in PMC: 2009 Dec 1.
Published in final edited form as: Health Care Manag Sci. 2008 Dec;11(4):399–406. doi: 10.1007/s10729-008-9067-6

Figure 1. Stylized example of the synchronization of a random event under a frequent screening scenario compared with infrequent screening.

Figure 1

For frequent screening, the “ith” random number determines the treatment effectiveness event with a result of “not effective” for a breast cancer diagnosed in an ‘early’ stage (solid arrow, first column). With common random numbers, the ‘ith’ random number is also used determine the treatment effectiveness event in the infrequent screening scenario regardless of the stage at detection. If it was detected in Stage III, treatment tendency is preserved as her treatment is again determined to not be effective (solid arrow, second column). Without common random numbers, the event may be determined by a different random number, the “jth” number, regardless of the stage at detection. If it was detected in Stage III, treatment tendency is not preserved as the result is “effective” (dashed arrow, second column).