求翻译：二手资料也有明显的缺点：二手资料的效度有时难以保证。有时候原始资料中包含一些错误和偏差，二次分析者对此不了解，可能使结论发生偏差。是什么意思？

Secondary data also have significant disadvantages: the validity of secondary data and sometimes difficult to guarantee. Sometimes contains some errors and deviations in the raw data, secondary analysis of those who do not understand this may make the conclusions deviations occur.

There are also 2 Mobile Information: 2 obvious shortcomings of mobile information may sometimes be difficult to guarantee the validity. Sometimes in the original source contains a number of errors and deviations, 2 times for the analysis does not understand that may make conclusions deviations occur

Two materials also have the obvious shortcoming: Sometimes two material validities with difficulty guaranteed.Sometimes in the firsthand information contains some mistakes and the deviation, two assayers did not understand regarding this, possibly causes the conclusion to have the deviation.

Second-hand information also has obvious disadvantages: validity of second-hand information is sometimes difficult to maintain. Sometimes the original data contains some errors and deviations, secondary analysis on this does not understand, could lead to deviation of conclusions.