Why are the statistics in Ezra 2 and Nehemiah 7 different?

Why are the statistics in Ezra 2 and
Nehemiah 7 different?
Ezra 2 and Nehemiah 7

     Ezra 2 and Nehemiah 7 are listings of numbered people from different families.  The chapters represent the statistics of the same families.  But they are not identicle.  I have produced a grid below that lists the families that do not match.  If you would like to see the grid comparing all families in Ezra 2 and Nehemiah 7, go here. 
     Of 39 entries (verses), 17 do not match.  They are listed below.

Ezra 2	Nehemiah 7	Difference
5 the sons of Arah, 775	10 the sons of Arah, 652	123
6 the sons of Pahath-moab of the    sons of Jeshua and Joab, 2,812	11 the sons of Pahath-moab of the     sons of Jeshua and Joab, 2,818	6
8 the sons of Zattu, 945	13 the sons of Zattu, 845	100
10 the sons of Bani, 642	15 the sons of Binnui, 648	6
11 the sons of Bebai, 623	16 the sons of Bebai, 628	5
12 the sons of Azgad, 1,222	17 the sons of Azgad, 2,322	1,100
13 the sons of Adonikam, 666	18 the sons of Adonikam, 667	1
14 the sons of Bigvai, 2,056	19 the sons of Bigvai, 2,067	11
15 the sons of Adin, 454	20 the sons of Adin, 655	201
17 the sons of Bezai, 323	23 the sons of Bezai, 324	1
28 the men of Bethel and Ai, 223	32 the men of Bethel and Ai, 123	100
33 the sons of Lod, Hadid, and Ono,      725	37 the sons of Lod, Hadid, and Ono,     721	4
35 the sons of Senaah, 3,630.	38 the sons of Senaah, 3,930.	300
41 The singers: the sons of Asaph,     128	44 The singers: the sons of Asaph,     148	20
42 The sons of the gatekeepers: the     sons of Shallum, the sons of Ater,     the sons of Talmon, the sons of     Akkub, the sons of Hatita, the     sons of Shobai, in all 139	45 The gatekeepers: the sons of     Shallum, the sons of Ater, the     sons of Talmon, the sons of     Akkub, the sons of Hatita, the     sons of Shobai, 138	1
59 and 60 list several names with     one total of 652	61 and 62 list numerous names     with one total of 642	10
65 besides their male and female     servants, who numbered 7,337;     and they had 200 singing men     and women.	67 besides their male and their     female servants, of whom there     were 7,337; and they had 245     male and female singers.	45 (singers)
17 discrepancies

      It is obvious from the above table, that there were many statistical differences between Ezra and Nehemiah.  Though most of them are identical, some do not match.  Why?  The answer is simple. 
     Ezra was written no later than 450 B.C.¹  Nehemiah should be dated during the reign of Artexerxes 1 (464-423 B.C.).²  According to the book, "Talk Thru the Bible," Ezra was written about 538-516 B.C.³ where Nehemiah was written around 444-425 B.C.⁴ Therefore, the dates of writing are different and the statistical differences can easily be accounted for by considering that during the difference of years, people died, families grew, etc. 
     I must note that there is a small percentage of copyist errors in numbers throughout the Hebrew Scriptures.  It is certainly possible that some of the numbers differ due to copyist mistakes.  Nevertheless, the difference in dates of writing can certainly account for the difference in numbers.

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1.  Harrison, R. K., Introduction to the Old Testament, (Grand Rapids, Michigan:  Eerdmans Publishing Company) 1969, page 1143.
2.  Harrison, R. K. page 1146.
3.  Wilkinson, Bruce and Boa, Kenneth, Talk Thru the Bible, (New York:  Thomas Nelson Publishers) 1983, page 116
4.  Wilkinson, Bruce and Boa, Kenneth, page 123.