When these series are detrended, however, either by using year as a control variable or by employing the method of first differences, the convergence between them is, in general, impressive. Thus, fluctuations in the UCR crime rates over time are paralleled by fluctuations in the NCS crime rates. If researchers detrend their data, as many time-series analysts do, then results based on UCR and NCS data are likely to be similar. This is encouraging news for those who use either set of data in time series-analyses. 3 figures, 1 table, 5 notes, and 18 references. (Author abstract)