How to Analyze Supplier Lead Times in Excel

1. Prepare the source and scope

Import operations.csv into a new worksheet with headers in row 1. Leave the source columns in their original order for the formulas below. Review the data dictionary before choosing the reporting period. Keep identifiers as text and convert numeric columns explicitly. Save a working copy so you can return to the original fixture.

2. Build the calculation

Average actual_days across the six example deliveries. Compare each delivery to promised_days and show the range as well as the mean.

=AVERAGE(M2:M7)

3. Reconcile and interpret the output

The expected check is mean observed lead time: 9.5 days. The mean covers six deliveries with equal weight. Keep planning lead time separate from observed duration. If your result differs, inspect the selected rows, data types and date filters before changing the formula.

4. Adapt the workflow to a recurring report

Replace the sample with a copy of your own source, retaining the same column meanings and units. Extend bounded ranges to include new rows, refresh PivotTables where used, and compare the result to an independent source total. Record the reporting period and any exclusions beside the output. Calendar days and business days are different measures and must not be mixed.