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. Author manuscript; available in PMC: 2013 Sep 13.
Published in final edited form as: Stat Med. 2010 Jan 30;29(2):181–192. doi: 10.1002/sim.3772

Figure 3.

Figure 3

Sample size ratio (SSR = Nθ/Nθ=0) comparing the required sample size of a study with CS response covariance (i.e. θ = 0) to a study with DEX response covariance (i.e. θ > 0) when the cumulative exposure effect model (4), CS exposure covariance, constant exposure prevalence and r = 5 are assumed, for several values of ρ and ρe. Lines indicate: (—) ρ = 0.2, (- - -) ρ = 0.5, (…) ρ = 0.8.