Peculiar history of demographic forecasts for Palestine

According to this article by Yakov Faitelson, most of the demographic forecasts for Palestine (and Israel) have proved to be completely wrong. As said in the article, demographic prediction is such an uncertain science that even Israeli specialists get it wrong repeatedly :)). Worth to read the excerpt below:

In a March 1898 letter, the famous Jewish historian, Simon Dubnow, criticized Zionist ideas, writing,

During seventeen years of tense work to encourage substantial emigration, after the expense of vast means and with the help of millions donated by Rothschild, we managed to place on the land of Palestine only about 3,600 settlers, which makes up approximately 211 people per year. Let us allow that the Western Zionist committees will work with significantly larger capitals and energy and will move to Palestine not two hundred, but one thousand settlers annually … then in a hundred years the Jewish population of Palestine will reach one hundred thousand men. Let's increase this number five times and add to this the natural increase and inflow of the industrial population to the cities, then we shall receive about a half million Jews in Palestine after one hundred years … Certainly, all of us treasure the hope to see at the beginning of the twenty-first century about a half-million of our brothers living in our ancient homeland, but can it solve the problem of 10 millions Jews, who are dispersed?

In May 1948, only fifty years after Dubnow's projections, the Jews in Palestine already numbered 649,600 people.
Such mistaken projections, however, have been the rule rather than the exception. At the end of 1944, Roberto Bachi presented to the Jewish National Council, the main institution of the Jewish community during the British Mandate, a secret demographic report that included four forecasts: optimistic and pessimistic, and with Jewish immigration as a variable. Bachi based his forecasts on the existing demographic data for 1938-42 and on estimates of trends that could be accepted as reasonable. He assumed that Arab fertility for the ensuing sixty years would continue to be very high (seven children or more per woman) or that it would decrease only slightly (six children per woman). He also assumed that Jewish fertility would remain at about two children per woman but might increase slightly to three children per woman. He also predicted that Jewish immigration might bring about one million Jews to Israel during the five to fifteen years starting from 1946.
These estimates could not be treated as prophecy, wrote Bachi, since the differences between reality and forecast increase as the projected time period lengthens. According to Bachi's pessimistic scenario, by 1971, the population of Palestine would include 2,467,000 Arabs and 604,000 Jews without Jewish immigration or 1,695,000 Jews should there have been one million Jewish immigrants. According to Bachi's more optimistic forecasts, the population of Palestine in the same year could consist of 2,186,000 Arabs and 698,000 Jews without immigration or 1,898,000 Jews with a million Jewish immigrants.
Fast-forward to 1971. Israel controlled the whole territory of the former British Mandate in Palestine, and 2,662,000 Jews already lived in Israel—about half a million more than in Bachi's most optimistic projection. The Arab population stood at 1,460,000, about one million fewer than he had predicted. Then in 1972, Bachi predicted, as he had in 1956, that immigration to Israel would stop as the Jews of the West were indifferent and the Jews of the Soviet Union were forever trapped. Nevertheless, over the next seven years, more than a quarter million Jews migrated to Israel.
His projections for 2001 were similarly off-base: According to the pessimistic forecast, the population of Palestine in 2001 would comprise 5,871,000 Arabs and 563,000 Jews without immigration or 1,580,000 Jews with a million Jewish immigrants. Following his optimistic forecast, the population of Palestine in 2001 should have been 4,415,000 Arabs and 831,000 Jews without immigration or 2,258,000 Jews with a million Jewish immigrants.
The reality was quite different. The Jewish population reached 5,025,010, nine times more than his pessimistic projection, and 2.2 times more than his most optimistic forecast. When combined with the immigrant population from the former Soviet Union, the total comprised 5,281,300 people. The total Arab population reached 3,570,000, some 1,300,000, or 39 percent less than Bachi's projection for 2001.
Israel's Central Bureau of Statistics forecast in 1968 that, by 1985, the Jewish population would increase to 2,923,000, and the Arab population would rise to 49 percent of Israel's total population. In reality, there were 3,517,200 Jews in 1985, representing 62.7 percent of the total population.
Amidst the 1987 Palestinian uprising against Israeli control in the West Bank and Gaza, demographic predictions—no matter how sloppy—became the stuff of headlines. In 1987, the Israeli newspaper Yedi'ot Aharanot quoted Arnon Sofer's bombshell forecast: "In the year 2000, Israel will become non-Jewish." The New York Times' Thomas Friedman picked up Sofer's prediction and ran with it in an 1800-word, page one story. Sofer claimed that by 2000 there would be "4.2 million Jews versus 3.5 million non-Jews. The 3.5 million Arabs would include: 1.2 million Israeli Arabs within the Green Line, one million Arabs in the Gaza Strip, and between 1.1 and 1.5 million in the West Bank." Sofer's tally indicated for 2000 a range of between 2.1 to 2.5 million Arabs in the Palestinian territories.
Putting aside the fact that the figures did not justify the headlines proclaiming a Jewish minority, Sofer actually miscalculated the Arab population twice: First, by using the 1986 Central Bureau of Statistics forecast made for 2002 for all Arabs—defined officially as citizens and permanent residents of the State of Israel, including East Jerusalem and the Golan Heights—as the Arab population of Israel only "within the Green Line," i.e., exclusive of East Jerusalem and the Golan Heights; and, second, by folding the Arab population of East Jerusalem into the forecast of the Arab population in the Palestinian territories. Then, he presented the forecast for the West Bank and Gaza Strip including East Jerusalem, as it was usually done by the U.N., CIA, and Palestinian sources. In effect, this results in double counting the East Jerusalem population, first as permanent residents of the State of Israel and then as the residents of Palestinian territory.
A month later, Sofer explained his forecast: "Without even considering birth rates, to make up one percentage point today, we need an additional 170,000 Jews ...Who among us really expects that sort of aliya (migration to Israel) in the near future?" Two years later, though, just such a migration occurred, underlining the inability of the demographers to forecast political developments. Over the ensuing decade, more than one million Jews were repatriated to Israel from the former Soviet Union. Including mixed Jewish families, this wave of immigration totaled 1.2 million people and increased Israel's Jewish population by 31 percent. Demographic prediction is such an uncertain science that even Israeli specialists get it wrong repeatedly.