Regression and threshold

What it is

A shelf-life study's detail screen brings together the study's tracking (completed, pending and overdue points) alongside three analyses: the sensory decay curve (the panel's real mean per time point, attribute by attribute), the sensory evolution curves (a fit computed from the data) and the per-attribute regression, which uses a linear model to estimate when each attribute will cross its acceptability threshold.

Access path

• URL: https://app.areacacao.com/sensory-analysis/studies/shelf-life/[id]
• How to get there: in Shelf-life studies, click the study card.

Detail sections

Header

Study title, status badge and, on a single line, the dates and references: Start:, Estimated end: and, only if you associated them, Recipe: and Batch: (these last two show as monospaced code when present).

Statistics

Five indicators summarize the study's progress:

• Points: completed out of the total.
• Pending: points not yet evaluated.
• Overdue: points whose scheduled date has passed without evaluation.
• Days elapsed: since the start.
• Evaluations: total accumulated.

Storage conditions

A reminder of Temperature, Humidity, Light and Packaging, along with the cadence Every N days · Duration N days.

Target attributes

The list of monitored attributes, each with its threshold.

Time points

A table with all the study's points: number, scheduled date, status, panellists and evaluations for each one. It's a tracking view.

Below it, the Study checkpoints section is where you record: each checkpoint has its own Record tasting button, and above them you'll see how many checkpoints have data and how many you still need before the curve is reliable. See Recording a checkpoint tasting.

Sensory decay curve

For each attribute, it plots the panel's real mean at each time point across the study, with its acceptance threshold line. It's the direct visual reading of how each attribute deteriorates (or holds up), based on the recorded evaluations.

While the series loads, you'll see "Loading time series…"; if the series can't be retrieved, "Couldn't load the study's time series." appears.

Sensory evolution curves

Below the decay curve, AreaCacao draws a second chart, the Sensory evolution curves: a fit computed from the panel's data that smooths each attribute's trend over time. Unlike the decay curve (which plots the observed mean point by point), this chart needs more data to be drawn.

Recommended sensory shelf life

Heading the regression section, AreaCacao boils the whole study down to a single figure: the recommended sensory shelf life, with its calendar date.

It is computed like this:

1. Of all monitored attributes, it takes the first one to cross its threshold — the one that sets the limit. That attribute is flagged with the Limiting attribute badge on its card.
2. The recommendation uses the conservative end of the 95 % confidence interval, not the point estimate. So if the central estimate says 25 days and the lower band says 20, the recommendation is 20 days. The point estimate is shown alongside for reference.
3. Rounding always goes down. A safety margin that gives days away is not a safety margin.

If no attribute crosses its threshold within the measured range, the card reports shelf life undetermined and suggests extending the study: you cannot recommend a shelf life the data doesn't support.

Shelf-life regression

This section appears with the title Shelf-life regression (OLS + 95% CI). For each monitored attribute, AreaCacao fits an ordinary least squares (OLS) linear model over the panel's means and computes:

• n: number of points used.
• Slope per day: how much the attribute changes each day.
• Intercept (day 0): estimated value at the start.
• r²: goodness of fit.
• 95% CI slope: 95% confidence interval.
• Min threshold: the one you set for that attribute.
• Days to threshold and estimated cross date: when the curve reaches the threshold.
• 95% CI conservative and 95% CI optimistic: range of cross dates according to the confidence interval.

Per-attribute regression statuses

Each attribute falls into one of these statuses:

• Cross detected: the curve is falling and the date it crosses the threshold is estimated.
• No decay: the attribute shows no downward trend.
• Already below threshold: the attribute is already below the threshold from the start.
• Insufficient data: there aren't enough evaluated points to fit the model.

While AreaCacao computes the model, the section shows the message "Computing OLS regression…" before the results appear. If the study has no target attributes configured, you'll see instead "No target attributes configured in this study."

Study status

The header shows the study's current status (active, paused, draft…) as a badge. Status management (pause, resume, complete or cancel) isn't yet available from this detail screen: although those actions are planned, they aren't wired up in the detail route yet.

Next steps