FOOD9102 Chap.6 Sensory Scales and Hedonic Acceptance Tests
Sensory Scales and Hedonic Acceptance Tests
Affective tests ask how much people like a product or which version they prefer. This chapter covers the Week 3 lecture’s scale vocabulary, nominal, ordinal, interval and ratio, and explains why the 9-point hedonic scale is treated as interval data that can be averaged.
It compares line scales with box scales, sets out the central tendency and relativity biases and the anchor points that correct them, and surveys the Likert, FACT, pictorial and just-about-right scales.
Choosing a scale is a design decision with consequences for the analysis: the scale type fixes which statistics are allowed. Chapter 7 picks up from here with the t-tests and ANOVA that interval data permit.
What this chapter covers
- 01
Acceptance tests and preference tests
- 02
Nominal, ordinal, interval and ratio scales
- 03
The 9-point hedonic scale and its scores
- 04
Intensity scales versus liking scales
- 05
Line scales, central tendency and relativity bias
- 06
Likert, FACT, pictorial and JAR scales
- 07
Why interval data cannot support magnitude claims
Worked example · free
Score a 9-point hedonic table for a new cereal
- 1Convert categories to scores 9, 8, 7, 6, 5 and 4, because the hedonic scale is an interval scale.
- 1Mean: (9 + 24 + 35 + 18 + 10 + 4) / 15 = 100 / 15 = 6.67.
- 1Standard deviation: 1.35, so report 6.7 ± 1.3, between like slightly and like moderately.
Key terms
- Acceptance test
- An acceptance test measures how much panellists like a product, usually on a hedonic scale.
- Preference test
- A preference test asks panellists to choose which of several products they prefer.
- Interval scale
- An interval scale has equally spaced points, so its responses can be averaged and compared statistically.
- Labelled magnitude scale
- The labelled magnitude scale is a ratio scale whose word labels are placed at quantified distances.
- Central tendency
- Central tendency is panellists' reluctance to use the extremes of a scale, even for products they love or hate.
- FACT scale
- The FACT scale rates a food by statements about how often the panellist would eat it.
- Pictorial scale
- A pictorial scale uses faces or stars in place of words so that children or less literate panellists can rate products.
Sensory Scales and Hedonic Acceptance Tests FAQ
Why is the 9-point hedonic scale treated as numeric data?
Because its points are equidistant, both on the page and mathematically. That makes it an interval scale rather than an ordinal one, so responses can be converted to scores from 1 to 9 and analysed with means, standard deviations, t-tests and ANOVA.
When would I choose a line scale over a box scale?
When you want more sensitivity, since a mark on a line can fall between whole numbers. The trade-off is consistency: panellists find it harder to remember where they marked a line than which box they ticked, and scoring a paper line by ruler takes longer than reading a box.
Can I say my product is liked twice as much as a competitor's?
Only with a ratio scale such as the labelled magnitude scale, which has a true zero. Hedonic and line scales are interval scales, so they support a significant difference in liking but not statements about how many times more a product is liked.
What scale suits young children?
A pictorial scale. The lecture describes smiley-face scales for young children, often used with parents helping to interpret reactions, and star systems for slightly older children, noting that the star system works well in western culture. Pictorial scales can also replace word labels for semi-literate adults.
Assessment move
Make a four-row table of scale types with an example ballot question and the permitted analysis for each, then classify every question on a real survey you have filled in. Practise converting a hedonic frequency table into a mean and standard deviation by hand, and memorise the line-scale biases with their fix. For the Week 7 laboratory, decide early which scale your own ballot will use and be ready to justify it.
When you design a ballot, read each question aloud and ask which scale type it really is; mislabelled scales lead straight to the wrong analysis.
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