AS 2542.2.3:2014 pdf free
AS 2542.2.3:2014 pdf free.Sensory analysis
A bipolar scale is used when the intensity of a property can differ in either direction from a neutral or ideal value. For example, a bipolar scale may run from“Not sweet enough” to“Too sweet”, whereas a unipolar scale may run from“Not at all sweet” to“Extremely sweet”.
When constructing bipolar scales, an inappropriate choice of scale anchors can produce a scale that does not form a true continuum and has no logical centre point. Avoid the use of anchors that are not based on a single attribute (e.g.“dark brown” to“bright red”) unless they lie on a recognized sequence of stages or grades of the product.
Assessors may be asked to make numerical responses on a continuous scale, meaning that numbers with fractional parts can be used. Line scales are typically 15 cm (6 in) long, labelled at each end with the extreme values of the attribute being assessed. The assessor responds by marking the line in the position corresponding to the perceived intensity. The marked position is converted to a number by the analyst.
A continuous scale gives assessors an opportunity to express small differences in judgement. On the other hand, the task may seem more dificult than using a category scale and transcription of the data takes longer unless an automatic data acquisition system is available.
There is no direct relationship between the response scale used and the measurement scale that corresponds to the values recorded. Thus the same response scale can lead to values that are only ordinal (unequal intervals) or that are on an interval scale (equal intervals).
In sensory analysis, it is the perception of a property that is assessed, not the property itself, and it is impossible to be certain that equality of the intervals has been achieved. While it is quite usual to interpret the results as if they correspond to an interval or ratio measurement scale, this interpretation should be expressed in each specific case as a working hypothesis.AS 2542.2.3 pdf free download.
