Data filtering is used to reduce the variable effect of spot area increases on growth curve modeling. (a) The increase in spot culture area, between 39 and 72 hours, is plotted for 96 replicate cultures (an 8 × 12 cell array). Internal and edge cultures are labeled differently to highlight the increases in spot area of edge cultures. (b) The spot intensity, spot area, growth rate (derived from a spline fit), and logistic-fitted growth curve are plotted vs. time to illustrate that the initial carrying capacity is reached about the time that the spot area begins to increase (after ~40 hrs in this example). Hence, late data are filtered to avoid the effect of this artifact on growth modeling with the logistic equation (see Materials and Methods).