Outlier

Under the declared median-of-halves convention, Juniper's 16 Year 2 values are split into ordered lower and upper halves of eight. The lower half's middle pair is 22 and 23, so (Q_1=22.5); the upper half's middle pair is 30 and 31, so (Q_3=30.5). The interquartile range is 8 days. The upper inner fence is:

[ 30.5+1.5(8)=42.5\text{ days}. ]

The 78-day invoice lies beyond that fence, so the rule flags it. The rule does not say why it is there.

Investigate the record, not the preferred answer

Trace the invoice to issue, due-date, dispute, payment, cash-application, and adjustment evidence. Check the unit and key, data entry, customer terms, partial payments, and definition of final settlement. Then choose a documented action:

• correct a verified recording or coding error;
• retain a valid observation in the primary analysis;
• report a robust or segmented analysis alongside it; or
• exclude it only when a predeclared population or data-quality rule supports exclusion.

Deleting 78 because it widens a confidence interval or weakens a preferred story is result-driven analysis. Automatically retaining a known duplicate or wrong-date record is no better.

Quartile conventions vary across software. The fence is a transparent screening convention, not a universal classification or proof that the data follow a particular probability model.