The coast/area ratio and the inland waterway (IWW) length show only limited correlation with total SSS volume.
As can be seen in Fig. 5, while all three parameters show limited correlation with Gleason score for low-grade tumors, they all show a dramatic increase at Gleason score 4 + 3.
However, using only these variables as instruments is likely to provide poor IV estimates due to limited correlation with V. Therefore additional variables that can work as instruments would be useful.
The number of variables considered in the multivariate linear regression analysis has been reduced by removing both the coast/area ratio and the waterway length, due to their limited correlation with the total SSS volume as well as with each of the four SSS segments considered in the analysis.
This implies that variation in omitted variables has only limited correlation with independent variables in our sample, which in turn means that our interpretations about how evaluation methods differ based on variation in uncertainty and controversy should have only limited bias.
Importantly, the volume of the pneumothorax can show limited correlation with the intensity of the symptoms experienced by the victim, and physical signs may not be apparent if the pneumothorax is relatively small.
