Two weeks ago I described the general trends we saw when analysing the force-displacement data from breaking Pringles that had been left unsealed for a varying number of days. I stated that the feature that showed most correlation with the age and hence the crispness was the amount of force peaks after the major force drop. We have since produced a graph showing this trend. The graph is displayed below, we used the standard error derived from the three sets of measurements at each age for the error bars.
To be absolutely sure that we found a trend we decided to redo the measurements under different conditions.