Figure 5.

Variance-based global sensitivity analysis. (A) First-order indices, indicating what fraction each model parameter (y labels) independently contributes to the variance of each model outcome (x labels). (B) Total Sobol’ indices indicate each parameter’s contribution to the variance of each outcome when considering all inter-parameter interactions. We calculated the Sobol’ indices using two independent sets of N = 10⁵ samples. Results indicate that all parameters make a statistically significant contribution to satisficing the desired model outcomes. However, the contribution of the rate constant for HOPS displacement by Sec17 is weak across all outcomes, and the SNARE chaperoning rate has little impact on fusion dynamics. Seven of the eight parameters strongly impact the steady-state criterion, but they do so almost exclusively through parameter interactions.