Experimental approach taken in this study. A. Copy numbers of the genetic devices in the model system were varied and the RNA from a particular device was measured as an output. B. DTC for a device (device x as an example) was generated by first plotting the RNA produced at each copy number. A regression that minimized the sum of squared residual error was subsequently fitted to the cumulative data. C. Linear system behavior was gauged by testing for superposition. Superposition was determined to exist if a correspondence was observed between the left and right hand sides of the depicted figure.