Handle missing and censored values

When a result is blank, <0.5 or hemolyzed, LabRuns keeps it exactly as written and flags its row. Before you calculate, correct each flagged row or exclude it with a reason. See Correct or exclude a result.

When a file holds such values, Import a file asks what to do with them: exclude them all with one reason, or keep them flagged and correct them later in Data. See importing a file.

An empty required result, on either side in a paired study, has a thin red edge. A notice above the grid counts the blank rows and offers one button for all of them. Use Go to first entry to reach a missing value, or Show details to choose an affected cell.

1. Choose the button in the notice, such as Exclude 3 rows. Blank rows are excluded with the reason Not measured. No value entered., or with the reason you already typed; the report lists them as not measured. Completely empty rows are removed. If all of them are empty, the button reads, for example, Remove 2 empty rows.
2. Choose Save changes or Calculate results.

Blanks are flagged in these fields:

• method comparison and qualitative agreement: both results
• linearity and near-cutoff: expected concentration and result
• stability: elapsed time and result
• interference: result, and interferent concentration on test aliquots
• other studies: the result

In a 21-position carryover study, a missing or excluded result leaves that run incomplete.

<0.5, ≤0.5, >1000 and ≥1000 are censored values: the result tells you only that the true value lies somewhere beyond the limit. The row stays flagged until you enter an exact value or exclude it. A detection-limits study can rank < results, as described below. In qualitative studies, <0.5 is flagged as an undeclared label.

• Exclude the row with a reason such as "Below the measuring range (<0.5 mmol/L)".
• Correct the value if an exact result is available.
• If many results are censored at the low end, consider a detection limits study.

In a detection-limits study, each <x result is ranked below every exact result, which a nonparametric LoB or LoB verification can use. The blanks' mean, SD and minimum are then not calculated. To flag < results as row errors, choose Treat “<” results as row errors under Set up › Calculation options › Censored results.

The calculation still stops if:

• x is above an exact blank result
• the LoB percentile falls among the censored results. Add more blanks.
• a censored result would enter a parametric LoB or an LoD

An LoQ material with a censored result is indeterminate. In detection limits, > and ≥ results are always flagged. See Detection limits.

Set up lists the result categories, by default negative and positive, and the nonreportable labels, by default equivocal, invalid and indeterminate. Case and surrounding spaces don't matter.

A nonreportable label is valid and counted separately:

• In qualitative agreement, a specimen whose first result is nonreportable goes in the Nonreportable row or column, outside the main table. It counts as a disagreement in the all-pairs agreement.
• In near-cutoff precision, it is counted in the Nonreportable column and left out of that concentration's hit rate.

Any other label, or a blank category, is flagged. Correct it, or add the label on Set up.

In a method comparison, a row with one result blank is flagged. Exclude it, or add the missing result to that row when it arrives. Importing the missing result as a new row doesn't complete the pair. See Reviewing an append or a replacement.

In an instrument comparison, a specimen missing on one instrument is still used wherever both results exist. For that instrument's specimen limit it counts as not evaluated, so the limit can't be met. In a lot comparison, a patient specimen measured on one lot only is listed as unmatched and counts as not evaluated, so the lot's specimen limit can't be met.