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Fitted fixed effects curves for 
simulated data sets: (a) fixed effects curve 
, (b)–(e) fixed effects curves 
, 
, 
, 
, (f)–(i) fixed effects curves 
, 
, 
, 
. Dotted lines denote true curves. Solid lines represent the averaged values of fitted curves. The upper and lower dashed lines are the 10% and 90% quantiles of the fitted values in 500 simulation studies.
