Measurement And Scaling Techniques: Scales Of Measurement ,sources Of Error In Measurement

Measurement and Scaling Techniques Scales of Measurement ,Sources of Error in Measurement

Levels of Measurement •

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We know that the level of measurement is a scale by which a variable is measured. For 50 years, with few detractors, science has used the Stevens (1951) typology of measurement levels (scales). There are three things, which you need to remember about this typology: Any thing that can be measured falls into one of the four types: The higher the level of measurement, the more precision in measurement and every level up contains all the properties of the previous level. The four levels of measurement, from lowest to highest, are as follows: Nominal Ordinal Interval Ratio

Four Levels of Measurement

Nominal scale  Data are numerical in name only  assigns number symbols to events in order to label them  assigns numbers for the purpose of categorizing events, attributes or characteristics  does not express any values or relationships between variables  mathematical or statistical operation that can be performed on nominal scales is a frequency run or count.

Ordinal Scale • It is the lowest level of Ordered Scale. • The ordinal level of measurement describes variables that can be ordered or ranked in some order of importance. • It describes most judgments about things, such as big or little, strong or weak. • Most opinion and attitude scales or indexes in the social sciences are ordinal in nature • The Ordinal Scale determines the students Rank in his class. Thus its use implies a statement of “greater than” or “lesser than” without being able to state how much great or less.

Interval Scale • The interval scales have more or less equal intervals, or meaningful distances between their ranks. For example, if you were to ask somebody if they were first, second, or third generation immigrant, the assumption is that the distance or number of years, between each generation is the same. • Interval Scales may have arbitrary zero, but it is not possible for them to determine what may be called as “absolute zero” or “a unique origin”.

Ratio Scale  a scale consists not only of equidistant points but also has a meaningful zero point  a ratio scale is an interval scale in which distances are stated with respect to a rational zero  ratios are equivalent  data allows forming quotients in addition to setting

Important Scaling Techniques 1. Rating Scales: • The Rating Scales involves qualitative description of a limited number of aspects of a thing or traits of a person. • We judge the properties of objects against the specified criteria, without reference to other similar object. • Three to seven-point scale are generally used for the reason that more points on a scale provide an opportunity for greater sensitivity of measurement.

• Rating Scale may be either a graphic rating scale or an itemized rating scale. • Graphic rating scale is quite simple and is commonly used in practice. The various points are usually put along the line to form a continuum and the rater indicates his rating by simply making a mark at the appropriate point on a line that runs from one extreme to the other. • Itemized rating scale presents a series of statements from which a respondent selects one as best reflecting his evaluation. These statements are ordered progressively in terms of more or less of some property.

2. Ranking Scales: • In this we make relative judgments against other similar objects. The respondents under this method directly compare two or more objects and make choices among them. ( Rank in the order of preference)