So let us evaluate the options for storing the meaning “missing” in a CSV file.
In the bad old days, which are still with us in some areas, lots of different identifiers were used to store the idea of “missing value”. There are times when the correct answer is zero and not “we don’t know.” Overcorrecting by storing the missing value deisgnator instead of zero can also cause problems for anyone working with the data.
Getting back to our original theme, missing values in Excel are identified by cells that are truly empty.
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It is important, therefore, to learn how to use the features of Excel to properly encode the meaning “missing value” whenever necessary.
One of the reasons spreadsheet software is so popular is that it allows users to the data they are working with, giving them a sense of control over the data.
By default, data entered into a cell can be of any type — string, float, decimal, date, .
One of the most important things an Excel user can do is to harness the built in validation tools every time new data are added.
If, instead, the data column is assumed to contain character strings, no error will be detected and the SPACE character will be used as a valid string.
The burden of checking for cells containing only whitespace characters and then converting these to missing values falls to the programmers working with the merged dataset.An earlier post described how to automatically convert an entire Acess database into a set of CSV files.The only problem with CSV as a standard is that it isn’t really standardized.“Seeing is believing” and most spreadsheet users seem to trust their own eyes more than they trust their software tools.Although we agree that human visual perception is an incredible tool for hunting ripe blackberries, we would argue that it is not evolutionarily suited to validating numbers and text.Here are a few we have encountered: The bottom line is that we recommend either “na” or “NA” as the missing value flag for CSV files. A lot of people have been taught that they overuse “me” and then overcorrect by using “I” even when the pronoun is the object of a verb or preposition. Two examples should get the idea across: The USGS Data Series 140 is a fantastic, century-long history of production and use data for a long list of minerals. Environmental Protection Agency issued a direct final rule that prohibits the use of chemical additives in gasoline for highway vehicles, effective January 1, 1996.