Ranking report
The analysis of the ranking test (ISO 8587): the Friedman test, a rank-sum table, and homogeneous letter groups.
What it is
The ranking report is the output of the ranking test (ISO 8587), in which each panelist places the samples in order according to a criterion —from least to most sweet, from least to most bitter, from least to most liked—. In chocolate making it serves to rank several samples along a single axis without asking for an absolute score for each one.
Unlike descriptive tasting, scores are not averaged here: you work with positions (ranks). That is why the analysis is not an ANOVA but the Friedman test, the right contrast for ordinal data with blocks (each panelist is a block that ranks the same set of samples).
Where to find it
- URL:
https://app.areacacao.com/sensory-analysis/evaluations/<id> - How to get there: open the ranking tasting under Evaluations and scroll down to the Results section.
Pro plan and above.
What the report shows
Friedman test
The report opens with the statistical verdict of the Friedman test, which answers a single question: did the panel rank the samples consistently, or is the order indistinguishable from chance? The report shows:
| Value | What it means |
|---|---|
| χ² | The Friedman statistic. The larger it is, the sharper the differences in position between samples. |
| Degrees of freedom (df) | They depend on the number of samples (number of samples minus 1). |
| p-value | The probability of obtaining this order by chance. If p < 0.05, there are significant differences between samples. |
A highlighted box translates the contrast: significant differences (the panel ranked the samples reliably) or no significant differences (you cannot claim the panel tells the sample order apart).
Rank-sum ranking table
A table orders the samples by their rank sum: the positions each panelist assigned to a sample are added up. Lower sum = better position on the ranked criterion (the sample most panelists placed first accumulates the lowest sum).
| Column | What it holds |
|---|---|
| Sample | Identified by its blind code while blind mode stays active. |
| Rank sum | The total of positions assigned by the panel. The lower it is, the better the position. |
| Group | The homogeneous-group letter (see below). |
Homogeneous letter groups
A letter (ᵃ, ᵇ, ᶜ) appears next to each sample. These are the homogeneous groups: samples that share a letter do NOT differ significantly from one another in order; those that share no letter do differ. It is the quick way to see which samples ended up tied for your panel and which truly stood apart.
The report also indicates the number of panelists who ranked all the samples: the Friedman analysis only counts those who completed the entire ranking, because it requires complete blocks.
How to interpret it
- A p-value below 0.05 confirms the panel ranked the samples consistently: the order is not coincidence.
- Read the table from lowest to highest rank sum: at the top is the sample best positioned on the criterion you ranked.
- Use the letter groups so you don't over-interpret: two consecutive samples that share a letter are, for practical purposes, tied for your panel, even if their rank sums are not identical.
- A no significant differences verdict does not prove the samples are equal: it means that, with this panel, no reliable order has been detected. Increasing the number of panelists gives the test more power.