There are four main reasons why it is not possible to perform reliable demographic analyses in East Europe for the 20th Century: the poor quality of Soviet censuses, the constant re-drawing of national boundaries which makes it impossible to compare like entities, the vast amount of population resettlements and migrations, and political noise.

For the important period of Russian-Soviet history there are only three censuses:

• the Great Census of 1897
• the All Soviet Census of 1926
• the census of 1959.

The totals for the three are approximately 125 MM, 145 MM, 175 MM. Now, the growth rate at the time of the first census was relatively high. If you project that out, then you should have something like 175 MM in 1926. But you have 145 MM. So you now have 30 MM "excess deaths", in other words, a shortfall in population projections. For the second census, from 1926 to 1950, the shortfall is anywhere from 30 MM to 50 MM "excess deaths." All arguments about the death tolls for the world wars, the civil war, two famines, collectivization, deportations, the Terror, the Holodomor, the typhus epidemics, etc. etc. come from these kinds of numbers. The problem is that these numbers are meaningless. And, even if there is, say, a 20 MM shortfall, how much gets assigned to, say, Nazi gas chambers, and how much to Soviet Gulags?

NOTE: there were other censuses besides the ones above but they were incomplete, results were hidden, sabotage alleged, and we are, after all, dealing with communists here.

The second thing is that all of the borders in central and eastern Europe changed at least once, and sometimes several times, in the first half of the 20th Century. Take for example the Germans. There were something like 20 MM ethnic Germans (i.e., people who spoke German as their mother tongue) living east of the Oder and south of Austria after World War One. Today, maybe 1-2 millions. What happened to all of these people?

Well, we know about the expulsions at the end of World War Two. Death tolls for this range from 2-3 million, out of an estimated 14 million expellees. This is based on a simple minded extrapolation, that says 14 Million Germans lived in Poland, Czechoslovakia, East Prussia, Silesia, Pomerania, Hungary, Romania, Yugoslavia at the end of World War Two. "Officially" there were zero Germans living in any of these places by 1950. The (fragmented and occupied) German governments, meanwhile, counted only 10-12 million "expellees" when they got around to counting them. What happened to these people?

Some died. Who knows how many. But others, probably, just hid out, blended in, fled, and so on. I mean, most East Europeans are multi-lingual. My read is that many Eastern Germans just blended in, if they were able to. Ditto the Jews.

What applies to ethnic Germans applies to each and every ethnic group in Central and Eastern Europe, including Jews and Gypsies.

The third thing is that from about 1900 to 1950 there were displacements and voluntary population movements for high tens of millions in Central and Eastern Europe. Large numbers of Germans, Poles, Ukrainians, Jews, and lesser numbers of Balts, Hungarians, South Slavs, and Eastern Slavs moved, were moved, or forced to move, for various reasons. A figure of 60 millions is usually given for the World War Two period and aftermath alone. In the first 50 years or so of the 20th Century, probably close to 100 million people were moved around. You would be lucky to get accurate statistics in an order of magnitude -- 10% -- if you were lucky and had all the relevant documentation.

Finally, there's the issue of political noise. Everyone lies about their losses. The Germans lied, until it became a crime to do so. Czechs, Poles, Russians, Ukrainians, Jews -- any other group you could mention -- routinely lie about their population losses. It's just the way the game is played.