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Update Control Charts

When you add rows to the data a chart was built from, Update rebuilds that chart from the larger range without asking you anything. You do not reopen the dialog and you do not re-enter the settings.

From Excel click...

QXL Stat Tools > Update, with the chart's own worksheet active.

The neighbouring Update Workbook button does the same thing to every VISIBLE analysis sheet in the workbook at once. Hidden sheets are skipped.

What It Does

Quantum XL stores two things when it creates an analysis: the dialog settings, hidden on the output worksheet, and a named range covering the cells the data came from. Update uses both.

  1. It reads the stored settings off the active worksheet.
  2. It finds the original data range through that named range, so it does not matter whether you remember where the data was.
  3. It regrows the range along the axis your data runs in. Column-oriented data grows downward to the last populated cell in each of its columns and keeps the same columns, so a new column beside the block is not picked up. Row-oriented data grows rightward and keeps the same rows. If the source was an Excel Table, it takes the table's current extent instead, which can grow both ways.
  4. It re-reads the data and re-runs the analysis with the stored settings.

New rows are picked up because of step 3, and the scan for them runs UPWARD from the bottom of the sheet, stopping at the last populated cell in each column. Two consequences are worth knowing:

  • A blank row between the old block and the new rows does not stop them being found. The blank rows are pulled into the range as well, and plot as gaps.
  • Anything else you have typed lower down the same column is pulled in too. Keep the column below your data clear, or a note parked at the bottom of the sheet becomes a data point.

Data typed into a different column is not part of the range and will not be seen.

What Changes and What Does Not

The control limits are recalculated from all the data, including the new rows, when the chart is using its default baseline of every subgroup. That is the usual case.

They are not recalculated if the chart was set to estimate from a fixed baseline. A chart whose Estimate Limits From setting was left on First N keeps the limits it already had, because that setting says which subgroups the estimate comes from, and adding more does not change the first N. New points are plotted against the limits that were already there, and can fall outside them. That is the point of a fixed baseline, and Update respects it rather than quietly widening the band. See Baseline and Limit Estimation.

Every dialog setting survives. The sigma multiplier, the rule set and its thresholds, splits, transformations, capability entries and display choices are all reused exactly. Only the data range, the source worksheet reference and the list of excluded outliers are refreshed.

When Update Is Refused

Situation What you see
The active sheet is not a Quantum XL output sheet This worksheet does not contain Quantum XL analysis data. followed by Please select a worksheet created by Quantum XL and try again.
No analysis of any kind is detected No Quantum XL analysis was detected on this worksheet.
The analysis was built from a single group of data rather than columns or rows Update is not supported for Single Group Data analyses. followed by Please use Modify instead to change the data range.
The original data range can no longer be found, usually because the source sheet was deleted or renamed The source data for this analysis cannot be found. with the internal reference name
The stored settings are unreadable or incomplete Failed to read analysis settings. or Stored analysis data is incomplete.

The single-group case is the one worth remembering: use Modify instead, which reopens the dialog with your settings in it and lets you point at a new range.

Charts Made by the Wizard

A chart produced by the Control Chart Wizard is built by the older engine and stores its settings a different way. Update still works on it, but it takes the older code path rather than the one described above. It is one more reason to prefer the ribbon's own chart entries over the wizard.

See Also