Simple Graphical Techniques for Calculating Serial and Spatial Correlations, and Mean Semi-Squared Differences

Summary Two methods of calculating these lag statistics from the graph of a series are described. One, the slide method, uses a scale printed on a glass plate; the other, the tracing method, requires no special apparatus. Both methods give results which are accurate enough for most needs. They may be used for evenly or unevenly spaced series, and are readily adapted to the analysis of concomitant and spatial series. For evenly spaced series, which alone are conveniently analysed on a desk calculator, the graphical methods compare favourably with it in speed. The tracing method is much quicker when the statistics are required for a large number of lags.