Macintosh (Macs) and PCs use internally different systems to count dates and this affects how the Excel program counts and shows the dates. Macs count dates from January 0, 1904. PCs count dates from January 0, 1900. In particular, Mac users normally will have the option "1904 dates" selected/enabled when preparing their Excel files, whereas PC users will not. This implies that dates prepared in Macs will appear in PCs to be 4 years off. It is possible to "toggle" between "1900" or "1904" date system in the Options:Calculate menu of your Excel program, and thus, the dates will change accordingly. However, we can't change this format in parts of a combined merged Excel file including data from Mac and PC users.

 

Therefore, if you are a Mac user and have prepared your Excel files with the "1904 date system", in order to help us handling appropriately your dates, we kindly ask you to set the date system to "1900" (unclick the "1904 sate system") in your computer and type in your dates as they correspond. Then, you can save your Excel file and submit it through this survey and be sure it will show exactly the correct dates which you have entered in your computer. Alternatively, upon setting the "1900 system", to avoid retyping correct dates, you could convert all "1904" dates to the "general" format (results in integer numbers), add 1462 to each cell, and the resulting amount reconvert it to "date" format, thereby restoring the date you initially had.

 

Thanks for your collaboration.