Explanation of Symbols:

4.2. Jam Values

Some data values represent unique situations where either the information to be conveyed is an explanation for the absence of data, represented by a symbol in the data display, such as "(X)", or the information to be conveyed is an open-ended distribution, such as 115 or greater, represented by 115+.

The following special data values can appear in the ACS Summary File table as an explanation for the absence of data:

Missing Value = ""

A missing string indicates that the estimate is unavailable. (This appears in the estimates and margins or error files as two commas adjacent to each other without anything between them, or if the last cell in a data file is filtered then you get a comma followed immediately by a carriage return or EOF.) A missing value indicates when an estimate is missing because of filtering for geographic restrictions, coefficients of variations (CV), or was removed due to the Disclosure Review Board's (DRB) requirements. For more detail on filtering, please visit Chapter 4.4.

Dot = "."

A dot indicates when the estimate has no sample observations or too few sample observations. In the margin of error files, this value could also indicate that the margin of error is unavailable for a median estimate that has been replaced with a jam value.

Zero = "0"

A "0" entry in the margin of error column indicates that the estimate is controlled. A statistical test for sampling variability is not appropriate. This is similar to the "*****" symbol used in American FactFinder.

Negative 1 = "-1"

This indicates that an estimate does not contain a Margin of Error. Tables B00001, B00002, and tables starting with B98 and B99 do not have margin of error (MOE) associated with them. The MOE calculations are set to -1 for these tables.

Jam Values for Medians

The following is a listing of the jam values for medians. For example, if there is an estimate of "2499" for table B10010, then it does not indicate a dollar amount. It means that the median is somewhere below 2,500 and thus is not calculated.

Jam Value Actual Meaning Use for Medians
2499 2,500 or less Income, Earnings
200001 200,000 or more Income
250001 250,000 or more Income, Earnings

Source: US Census

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