Population of Ottoman Palestine
The population of Ottoman "Palestine" is difficult to estimate, because:
1. There was no administrative district of Palestine. Turkish census figures were for various districts, including the Jerusalem, Acco and Nablus districts for example. The Acre district included areas in Lebanon, outside the modern borders of Palestine in which there were no Jews.
2. Turkish census figures did not include Bedouins (estimated at a few thousand) and foreign subjects. A considerable proportion of the Jews retained their foreign nationality (usually Russian) in Ottoman Palestine.
3. Both Arabs and Jews avoided the Turkish census. Foreigners who were without residence permits did not want to make their presence known. Arabs and Jews wished to avoid taxes and conscription.
4. In the 19th century, only Muslims were subject to the draft, and accordingly, Muslims tended to avoid the census.
5. According to Justin McCarthy, the census tended to undercount women and children.
6. The Turkish census data were not published regularly, so only partial data are available.
As the data are ambiguous, different sources give different estimates. In particular, Zionist sources may exaggerate the number Jews in earlier years and undercount Arabs, and Arab sources According to Bachi, (cited here) there were there were 489,200 Arabs (Muslims and Christians) in Palestine in 1890 and 42,900 Jews.
According to Beinin and Hajjar the Turkish census for 1878 listed 462,465 Turkish subjects in the Jerusalem, Nablus and Acre districts: 403,795 Muslims (including Druze), 43,659 Christians and 15,011 Jews. In addition, there were at least 10,000 Jews with foreign citizenship (recent immigrants to the country), and several thousand Muslim Arab nomads (Bedouin) who were not counted as Ottoman subjects.
However, according to the data of Karpat, cited here, in the Ottoman Turkish Census of 1893, there were 371,959 Muslims and 42,689 Christians, for a total of 414,648 Arab Palestinians, and only about 9,000 Jews. The data of Beinin and Hajar probably include subdistricts of the Acre Sanjak that are in modern Lebanon. Everyone agrees that the numbers for Jews and Muslims are far too low. Rupin (cited in the same article here) claimed there were a total of 689,275 persons in Palestine in 1893, of whom about 80,000 were Jews. This number is probably an overestimate.