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Options¶

This page is the control by control reference for the dialog titled Create Trellis Charts. What the finished chart shows is on Trellis, and how each panel's values are formed is on Math Details.

This dialog carries a control no other chart dialog has. Everywhere else the ribbon command decides what is drawn. Here the ribbon has one Trellis command and the Chart type box inside the dialog chooses between a surface, a contour and an interaction plot, so one panel can be any of the three.

Outputs¶

The left side of the dialog is a box headed Outputs holding a tree with three levels: the worksheet, then each output on it, then each level of that output. Tick the levels you want a chart for. The dialog opens with every level on the active sheet already ticked.

The two upper levels are three-state. Ticking a worksheet or an output ticks everything under it, and clearing it clears everything under it. When only some of the children are ticked, the parent shows a partial state rather than a tick, so the tree tells you at a glance whether a selection is complete.

One worksheet at a time. Ticking anything on a second worksheet silently clears every tick on the one you had selected, and the options on the right rebuild for the new sheet. There is no warning and no way to draw charts from two source sheets in one Create.

If you press Create with nothing ticked, the dialog tells you At least one chart must be selected. and stays open.

This chart is built from a regression sheet only. Design sheets are not offered, because the chart plots a value that only a fitted model can produce.

The level lines therefore always read the fitted names. Under a quantitative output the two levels are the output's name followed by Y-Hat and by S-Hat, the second offered only when the output has a usable standard deviation model. Under a binary output the two levels are written probability of followed by the event name and then the non-event name. Under a nominal output there is one line per level, and the last carries (reference level).

One trellis worksheet is written per ticked output level.

Chart type¶

A box headed Chart type offers three radio buttons: Surface, Contour, and Interaction. Surface needs at least one of the two primary factors to be continuous; Contour needs both continuous; Interaction accepts any pair, continuous or categorical. A type that the current primary pair cannot support is greyed out and cannot be chosen, and the note below the three buttons states why: "Surface needs at least one continuous primary factor; Contour needs both continuous; Interaction works with any primary pair." Surface is selected by default.

Changing the primary factors so the current chart type no longer qualifies switches the choice automatically: away from Contour to Surface when only one primary factor is continuous, and to Interaction when neither is (since Interaction always qualifies).

A trellis needs at least three factors of the design: two for the primary axes and at least one left over to split the panels (the block counts as a factor here, so it can serve as a panel variable). When the selected source has fewer than three, the Chart type, Primary factors, and Panel variables boxes are disabled and a message reads: "A trellis needs at least three factors: two for the primary axes and one to split the panels. This source has fewer, so a trellis cannot be drawn. Use an interaction or surface plot instead."

Primary factors¶

A box headed Primary factors holds two dropdowns, Horizontal axis (X) and Series axis (Y), each listing every factor of the design (plus block, when present, spelled lower case as the product spells it). They default to the first two continuous factors found, or, failing two continuous factors, the first two factors of any kind. The two must be different factors; pressing Create with the same factor in both reports The two primary factors must be different.

For a Surface or Contour trellis, when the axis holds a continuous factor a From / to pair of boxes appears beneath it, defaulting to that factor's actual range, with the range repeated as text underneath; both boxes accept only a number and carry no built-in minimum or maximum. These range boxes are not shown for an Interaction trellis, which draws the factor's actual levels rather than a swept range. A Surface or Contour trellis applies the same continuous-on-horizontal swap Surface Plot does: if the horizontal axis ends up categorical while the series axis is continuous, the two are exchanged before drawing.

A surface trellis moves a categorical primary factor to the series axis for you. If Horizontal axis (X) holds a categorical factor while Series axis (Y) holds a continuous one, the two are swapped before drawing, so the continuous factor is the one that gets a plotted range. This is the same swap the single Surface Plot makes, and it is the reason a surface trellis needs only one continuous primary factor rather than a continuous one in a particular box.

An interaction trellis makes no swap and reads no range. Both primary factors are used exactly as chosen, the horizontal one along the axis and the other one supplying the separate lines, and an interaction chart draws the factor's own settings rather than a swept range, so the From and to boxes have no effect on it.

When a chart type and a primary pair disagree, the message names the type. A contour with a categorical primary factor reports A contour trellis requires both primary factors to be continuous., and a surface with two categorical primary factors reports A surface trellis needs at least one continuous primary factor. Two categorical primary factors need an Interaction trellis. In practice the greying out described above reaches you first.

Panel variables¶

A box headed Panel variables carries a note: "One panel variable produces a row of panels. Two produce a grid (first = columns, second = rows)." It holds one required First panel variable editor and a checkbox, Add a second panel variable, unchecked by default, that reveals an identical Second panel variable editor when ticked. Neither panel variable can be one of the two primary factors; choosing one that is reports The first panel variable cannot be one of the primary factors. (or the same message naming the second). The two panel variables, when both are present, must differ from each other, or pressing Create reports The two panel variables must be different.

Each panel-variable editor starts with a Factor dropdown listing every factor of the design. For a continuous factor it is followed by a From / to pair (defaulting to the factor's actual range) and a Slices count box on its own row, defaulting to 3. The From and to boxes accept only a number; the Slices box accepts only a whole number, and must be at least 1, or Create reports The number of slices for [factor] must be a whole number of at least 1. One panel is drawn for each slice. A range that reaches outside the factor's experimental range does not block the chart: pressing Create instead raises a prompt naming the factor, the range typed, and its experimental range, asking whether to create the trellis anyway.

For a categorical factor (or the block), the panel-variable editor instead shows one checkbox per level, none ticked by default; one panel is drawn for each ticked level, and leaving every level unticked reports Tick at least one level of the panel variable [factor].

One slice is allowed and draws one panel. A Slices count of 1 puts the single panel at the From value, not at the midpoint of the range and not at the to value, so a trellis of one panel is a chart at the low end of whatever range is in the boxes.

Set points¶

A box headed Set points (factors held constant) lists every factor that is neither a primary axis nor a panel variable; its value is fixed the same way in every panel. Each row follows the same rule as the surface panel's set points: a continuous factor is an editable box defaulting to the midpoint of the factor's uncoded valid range with that range shown beside it, accepting only a number with no built-in minimum or maximum and raising the same "create anyway" prompt when the typed value reaches outside that range; a categorical factor is a fixed dropdown of level names defaulting to the last level shown. Unlike the other five panels, this box has no source-based hide rule: Trellis is regression-source only, so it is always shown when there is at least one factor left to hold constant.

A box never holds a value that is not a number. This is true of the primary range boxes, the panel range boxes, the Slices boxes and every set-point box alike. A box commits what you typed only when focus leaves it, and an entry that does not parse is rejected at that moment rather than committed. Pressing Create while a box is still showing a rejected entry reports One or more entries are not a valid number. Correct the highlighted boxes and try again., moves focus to the first such box, and creates nothing.

Several further messages exist in the code for the same conditions, checked a second time when Create builds its selections, among them The range for the panel variable name must be numeric. and The number of slices for name must be a whole number of at least 1. The boxes' own rejection means the panel never has a non-numeric value to hand over, so these are not reachable from the dialog.

Before it draws¶

The number of panels a choice would draw is the first panel variable's slice or ticked-level count, multiplied by the second's when a second panel variable is added. If that count exceeds 16, pressing Create raises a prompt before drawing anything, naming the panel count and warning that this many panels can be slow to draw and hard to read, then asking whether to create it anyway. Answering no returns to the dialog with every choice intact.

If anything you typed reaches outside the range the factor actually took in the data, the software asks before drawing. A set point is one source of that. On the dialogs that carry axis range boxes, which are Surface Plot, Contour Plot and Trellis, a From or to value counts too, as does a trellis slice range, so widening an axis past the experimental range raises the prompt on its own with every set point left alone. The prompt lists each offending entry with the factor's experimental range beside it, warns that the chart will extrapolate beyond the data, and asks whether to create it anyway. Answering no returns you to the dialog with your options intact.

This is a warning, not a refusal. A prediction outside the range of the data is an extrapolation of the fitted model, and the model was never tested there.

A panel variable's slice range counts toward that prompt too, alongside the primary axis ranges and the set points, so widening the span a trellis conditions on raises it with every other box left alone.

While it draws¶

While charts are being written, a status line reports what is happening and a progress bar appears only when more than one chart is being drawn, since a bar for a single chart would sit at 100 percent from the moment it appeared.

Cancel stops the run cleanly between charts, not part way through one. A chart that has already been written stays; the sheet that was mid-write is deleted rather than left half finished. So cancelling never leaves a partial chart behind, but it can leave fewer sheets than you asked for.

Creating with the dialog left open lets you build several charts from one set of options without reopening it. The charts are identical either way: the only difference is whether the window closes afterwards.

When nothing is drawn¶

If the options you chose produce no drawable chart, the dialog reports There are no valid charts selected for the report. and writes nothing. Where the reason is specific, for example an axis rule or a source restriction, that more specific message is shown instead.

The dialog is owned by the Excel window, so Excel cannot cover it while it is open. If it seems to have vanished, it is on another monitor rather than behind the workbook.