Previous observations of thin metallic ion layers occurring in the lower E region of the polar cap have suggested that such layers drift horizontally, but this impression had not been confirmed by direct measurement of plasma motion within the layers. In this paper, we describe a technique for finding the drift velocity of a thin ion layer, based upon statistical analysis of data gained from an incoherent-scatter radar experiment, i.e., line-of-sight velocities deduced from Doppler analysis of the power spectra of backscatter from within the layer. We applied this technique to two typical layers observed over Sondrestrom and found that considerable horizontal drift was present in both cases. This finding has significant implications for studies of the formation and subsequent time evolution of thin metallic ion layers. In addition, our statistics-based algorithm can readily be adapted to radar studies of other geophysical phenomena, e.g., determination of F region electric fields.