Will the Roster Hold Tonight?
Put in the patients, the nurses rostered and how often people call off and get back the odds the shift runs short. Twenty-seven patients, six nurses, four and a half each. The sheet says the shift is fine. Ten thousand simulated nights say it runs below ratio on a third of them, and call-offs, not the census, are why.
Nursing Intermediate Monte Carlo Pro engine
After you install, this is the model to open.
Will the Roster Hold Tonight?
- In your spreadsheet, click the Sortia icon in the strip of icons down the right-hand edge. No strip? Click the arrow at the bottom-right to open it. You can also use Extensions, then Sortia, then Open Sortia.
- Click Start from a template and put that name in the search box.
- Pick the card with that name and click Load this template. It arrives on a new tab with real numbers already in it.
This one runs on a Pro engine, and every free install includes five full-quality runs on your own numbers, shared across all five Pro engines rather than five for each. After that, Pro is $199/year.
What it does
A 30-bed medical unit on nights. Twenty-seven patients, a one-to-five ratio, six nurses rostered. On the sheet it is exactly right: six required, six on the floor, 4.5 patients each, nothing short. That is the roster a manager posts and stops thinking about. Two things about tonight are not actually known when the roster is posted, and they are the two the sheet fills in with a single number.
The census is not 27, it is somewhere between 21 and 30. And nobody calls off until they call off. Click Run. The unit runs below ratio on about 34 of every 100 nights. Nurses short comes back at zero for the median, but the 75th percentile is one, the 90th is two and the 99th is three. Patients per nurse has a median of 4.69 and looks fine, and then the ladder keeps going: 6.26 at P90, 6.88 at P95, 8.93 at P99, and 9.86 at the worst night in ten thousand.
A nurse with ten patients is not a staffing variance, it is the night somebody gets hurt. Now read the tornado, because it changes what you would do about it. Call-offs correlate 0.91 with running short. The census correlates 0.17. Call-offs matter roughly six times as much as how many patients turn up, and that is the opposite of where the effort usually goes: units build census forecasts and treat call-offs as weather.
The lever is cover, not prediction. Two runs worth doing. Change RNs rostered to seven and rerun: the below-ratio share drops sharply, and you can price that seventh nurse against what a below-ratio night costs you. Then put your own call-off history into the discrete distribution in the panel, because the numbers here are a plausible unit and not yours, and this is the one input worth measuring rather than guessing.
What the model cannot see is acuity. It counts patients, and four stable patients are not two fresh post-ops and two confused falls risks, so a shift that clears the ratio can still be unsafe. Ratio is the floor the law cares about, not the ceiling the ward needs. To make it yours, put your bed count, your ratio and your own roster in, and set the census range from your own last three months rather than from a feeling.
The model
It arrives on a tab called Template: Will the Roster Hold Tonight:
| Night shift cover, 30-bed medical unit | |
| Patients on the unit tonight | 27 |
| Nurses the ratio requires (1 to 5) | 6 |
| RNs rostered for the shift (count) | 6 |
| RNs who call off | 0 |
| RNs actually on the floor (count) | 6 |
| Nurses short of the ratio | 0 |
| Shift runs below ratio | 0 |
| Patients per nurse on the floor (ratio) | 4.5 |
Once it is in your sheet
- The model arrives with real numbers in it and runs as it stands, so you can press the button first and understand it second.
- Change the numbers to yours. The sheet marks which cells are inputs and which hold formulas, and most labels carry a note explaining the row.
- Press the run button at the bottom of the panel. It is labeled for the tool you are in, and the result lands on its own tab, with a written reading of it beside the figures.
Never used Google Sheets? Start here goes the whole way, in seven steps, and assumes nothing.
Next question
- Put in the shifts each nurse works and get back who carries the weekends and nights. Eight nurses, twelve shifts each, and it still is not equal: one works five weekends and one works one. The month looks fair in total hours and is not fair in the hours anybody minds.Is the Roster Fair?
- Put in the shift hours, the rate and your tax and costs and get back what the extra shift really leaves you. A twelve-hour overtime shift at $42 an hour with a night differential grosses $822 and leaves you $431.96. That is $36 an hour for a shift that pays $63, and just over half of what it looked like.Is the Extra Shift Worth It?
- Thirty-six hours of vacancy costs $2,268 on your own staff and $3,520 through an agency. The agency only wins if your overtime multiplier reaches 2.33, and almost nobody pays that.Overtime or Agency?
- Two nurses on call cost $624 on a normal night. Across ten thousand simulated nights they average $808, and the worst reaches $3,396, which is the number the stipend line never shows.How Many Nurses on Call?
- Put in the posts, the turnover and the time to fill and get back the empty posts and cover cost to expect. A 42-post unit at 19% turnover carries about two empty posts all year and $253,000 of cover. Filling posts faster matters more than losing fewer nurses, and the tornado says so.How Many Nurses Do We Need to Hire?
- Two experts, one schedule. Where is the settlement zone?Delay Claim: Who Owns the Days?
Every model like this one, and the method behind them: Monte Carlo simulation.