Baselines, slip bars and the data-date curtain: a variance story in one view
The monthly report shouldn't need a variance table. Set a baseline, switch on slip bars, fill progress to the data date and drop a status line — and the whole story tells itself in one picture: what slipped, by how much, and what's quietly running ahead. Here's how to build it, and how to read it.
Every progress meeting has the same awkward moment. Someone pulls up a grid of columns — baseline start, baseline finish, actual start, actual finish, start variance, finish variance — and the room goes quiet while people try to do arithmetic in their heads. Which activities slipped? By how many days? Is anything actually ahead? The numbers are all there. Nobody can see them.
Variance is a visual idea trapped in a spreadsheet. The fix isn't more columns — it's a picture that puts the plan and the reality on the same row, so the gap between them is the slip. Set that up once and your monthly report answers the two questions a sponsor actually asks — what's late, and what's early — before you've said a word.
What each mark means
A slip-bar view has exactly four moving parts, and once you know them the whole picture reads instantly:
- Ghost bar (baseline) — the frozen plan. Where each activity was supposed to sit. It never moves; that's the whole point of a baseline.
- Solid bar (current) — where the activity sits in the live schedule now: its actuals so far, and its forecast to complete.
- The gap — the horizontal distance between the ghost and the solid bar. Solid to the right of the ghost = slipping. Solid to the left = ahead. Sitting exactly on top = on plan.
- The data date — a dashed vertical line that splits the world in two. Everything left of it is claimed history (progress you've reported as done). Everything right of it is forecast (what's still to come). It's the curtain between what happened and what you're promising.
Read together, they carry the entire variance narrative. You don't compute finish variance — you see it as the overhang. You don't hunt for what's ahead — an activity whose solid bar has pulled left of its ghost is ahead, and it jumps out because the colour of the gap flips.
Set it up in four moves
Take a small, honest example — four activities on an early works package. Two have slipped, one's holding, one is running ahead of plan. Here's how to turn a raw schedule into the report that shows all of that at once.
- Set or import a baseline. Freeze the current dates as the baseline (or bring in an approved baseline from your P6/MSP export — the as-planned dates ride in with the file). This is the ghost you'll measure everything against; snapshot it before the first update, not after things have moved.
- Turn on slip bars. Flip the baseline display on and Sketchedule draws each baseline bar as a faint ghost under the current bar, with the gap between them shaded. Every row now shows plan-vs-actual on one line — no variance column needed (Fig 1).
- Set the data date and fill progress. Drop the data date to the reporting cut-off; it appears as a dashed red line across the chart. Enter % complete (or actual start/finish) per activity and the bars fill up to that line — claimed history solid, forecast faded (Fig 2).
- Add the status line. Draw the progress/status line — it threads through where each activity has actually reached. Where it bulges left of the data date, that work is behind; where it bows right, it's ahead. One zig-zag line, and the whole package's ahead/behind reads at a glance (Fig 3).
Where the variance story gets buried
Desktop schedulers can absolutely compute all of this — baseline start, baseline finish, start and finish variance, days late — and they'll happily give it to you as columns. That's the trouble. The variance story ends up scattered across six numeric fields on each row, and a director reading a printout has to reassemble it in their head, one activity at a time. The moment it's a table, it stops being obvious.
The category habit is worse still: export the grid, screenshot it into a slide, and paste a colour-coded variance table under a title. Now the picture is a spreadsheet of a spreadsheet. Nobody looks at a variance column and feels a slip; they feel it when they see the current bar hanging out past the ghost, coloured red, with a status line sagging behind the data date. Same data — one is legible, one is homework.
That legibility is the whole job here: put the plan and the reality on the same row and let the gap speak. One clean picture instead of a wall of columns.
Two ways to get it wrong
Baselining after the horse has bolted
A baseline snapped after the schedule has already moved isn't a plan — it's a photo of the delay. The ghost bars will sit under the current bars and everything looks on track, because you froze reality, not the promise. Baseline the approved plan before the first update, and keep it frozen: the value of a baseline is that it doesn't move when things go wrong.
Progress that outruns the data date
If an activity's % complete implies work finished to the right of the data date, the picture quietly lies — you can't have done work in the future. Bring progress honestly to the cut-off, let the fill stop at the line, and the status line tells the truth. A slip bar is only as honest as the progress you feed it.
| You see | It means | Do next |
|---|---|---|
| Solid bar right of the ghost, red gap | Slipping — finishing later than planned | Check the driving logic in P6; is it on the critical path? |
| Solid bar left of the ghost, green gap | Ahead — beating the baseline | Bank it, or reallocate the float downstream |
| Fill stops short of the data date | Behind on work done, whatever the dates say | Re-check % complete against site reality |
| Status line bowing right of the data date | That workstream is running behind now | Focus recovery there before it reaches a milestone |
Key takeaways
- A slip bar puts plan and reality on one row — the gap between ghost and solid is the variance, no column needed.
- Ghost = baseline, solid = current, gap = slip. Right and red is late; left and green is ahead.
- The data date splits claimed history from forecast — progress fill stops at the line, and the status line shows ahead/behind at a glance.
- Baseline the approved plan before the first update and keep it frozen, or the ghost photographs the delay instead of the promise.
- The variance is presented, not recomputed — P6 / MS Project still own the network and the numbers.
Turn your next report into one picture
Open Sketchedule in a browser — free, no install, nothing uploaded. Set a baseline, switch on slip bars, and let the variance tell itself.
Primavera and P6 are trademarks of Oracle Corporation; Microsoft Project is a trademark of Microsoft Corporation. Sketchedule is an independent product and is not affiliated with, endorsed by or sponsored by Oracle or Microsoft. Figures are illustrative, drawn in Sketchedule; Fig 3 is a faithful redraw of a baseline-vs-current early-works view built in the app.