Beginning in the late 1970s, a lengthy debate was carried on among Western scholars about the scale of the Stalinist terror of the late 1930s (the Great Purges). The discussion was stimulated by works like Solzhenitsyn's The Gulag Archipelago and Roy Medvedev's Let History Judge that were smuggled out to the West or circulated in samizdat in the Soviet Union. Drawing primarily on the testimony of individual survivors and their families, these works gave an exceptionally valuable qualitative picture but could not answer quantitative questions. Since little hard data was available, Western Sovietologists' estimates of the number of victims of the Great Purges of 1937–8 varied widely, ranging from hundreds of thousands of deaths to tens of millions.

Sovietologists like Robert Conquest – “cold warriors,” as they were sometimes called by scholars of the younger generation – offered very high estimates of the number of Great Purge victims and regarded disagreement with their figures as prima facie evidence of pro-Soviet bias. “Revisionist” Sovietologists, for their part, thought the traditionalists' figures were exaggerated because of their anti-Soviet bias. In addition, some demographers and social scientists trained in quantitative methods argued that the highest figures were nonscientific and statistically implausible.

It was in 1978, in the context of this debate, that I first thought of using Soviet telephone directories as a data source on the Great Purges. It seemed improbable at that time that the data on Stalinist repression locked in Soviet archives would become available in the foreseeable future, and under these circumstances, any possible avenue seemed worth exploring.