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CSV missing-value analyzer

Count blank, NULL, NA, and other common missing-value markers by CSV column.

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How to use

Use this before a bulk import to see which columns contain blanks or placeholder missing values. In addition to empty cells, you can treat markers such as null, na, n/a, and undefined as missing.

  1. Paste the CSV.
  2. Adjust the comma-separated missing markers if your source uses different placeholders. Blank cells always count as missing.
  3. Review missing counts and percentages by column, then compare them with which fields are actually required.

When is this useful?

Missing-data patterns are hard to see by scrolling. A column with 27% missing values can hide inside a file that otherwise looks fine. Column-level percentages help you spot extraction problems or required fields that need attention.

The important thing to know

“Missing” is not limited to an empty string. Exporters often write literal markers such as NULL or N/A. The configured markers are matched case-insensitively. Values such as 0 and false remain real values unless you explicitly add them as markers.

Common traps

  • A high missing rate is not automatically bad; optional fields can legitimately be sparse.
  • If you add a real business value to the marker list, it will be counted as missing.
  • Whitespace-only cells become blank after trimming.

Example

A customer file might show 2% missing email, 63% missing phone, and 0% missing customer ID. That could be perfectly fine if phone is optional—but a missing customer ID may be a reason to stop the import.

How to read the result

Do not fill columns just because their missing percentage is high. First ask whether the field is required. A sudden gap in a required ID can signal extraction trouble; a sparse optional phone field may be perfectly normal. Missing rate is a triage signal, not a repair command.