Recently, it was noted by Park \& Gott (1997) that there is a statistically significant, strong, negative correlation between the image separation $\Delta\theta$ and source redshift $z_{\mathrm{s}}$ for gravitational lenses. This is somewhat puzzling if one believes in a flat ($k=0$) universe. Here, I look at possible causes of this effect and whether or not it is useful as a general cosmological test, using some data from the JVAS and CLASS surveys.
The links below point to one file (in each case) containing the complete text, all figures and tables etc.
As are most of my publications this is available in more than one form: