目前在写泰国对外直接投资相关的论文，但是却被数据困扰了很久，还希望各位大佬可以指点一二。
在IMF的CDIS数据库中找到了泰国对外直接投资头寸（存量）数据，但某些国家的数值与泰国央行所找到的数据差别较大。
还有就是，为什么IMF的存量数据会存在负数呢？
这是它在文件最后附上的注释：
Direct investment positions are negative when a direct investor’s claims (equity and/or debt) on its direct investment enterprise are less than the direct investment enterprise’s claims (equity and/or debt) on its direct investor.Direct investment positions also could be negative due to net negative positions with fellows.  Direct investment positions also can be negative due to negative retained earnings (which may result from the accumulation of negative reinvested earnings).

我目前的困扰是：IMF数据的年份更多、但却存在负数，且和泰国央行统计的相差较大，这种情况下应该如何处理呢？