4/25/2015Marketing Research2 MEASUREMENT An attempt to provide an objective estimate of a natural phenomenon ◦ e.g. measuring height ◦ or weight
4/25/2015Marketing Research3 Measurement scales Nominal Scales ◦ Categories - mutually exclusive and collectively exhaustive. Ordinal Scales ◦ Rank order – e.g. most important to least important. Interval Scales ◦ Ordinal + the intervals between data points are equal. Ratio Scales ◦ Above + a meaningful absolute zero or origin.
4/25/2015Marketing Research4 Measurement scales: Example How could you measure height using the following levels of measurement? ◦ Nominal Scales ◦ Ordinal Scales ◦ Interval Scales ◦ Ratio Scales
4/25/2015Marketing Research5 Measurement error Evaluate my bathroom scale: Is it ACCURATE?
4/25/2015Marketing Research6 Reliability Consistent results over time. Measures are free from random error. Test-Retest Reliability: Obtained by repeating the measurement using the same instrument under as nearly the same conditions as possible.
7 Test and Retest: One instrument is used at two different times under similar conditions to the same people. Equivalent Form: Two similar versions of an instrument are administered at two different times to the same people. Spilt Half: Two versions of the same instrument (half of the items) are administered to different people, but compared to one another. Testing Reliability
4/25/2015Marketing Research8 Validity Addresses the issue of whether what we tried to measure was actually measured. How do I know if my bathroom scale is valid? That is, does 160 really MEAN anything? How could I know this with my bathroom scale? 1.JUST using the same scale 2.Using ANOTHER scale.
4/25/2015Marketing Research9 Types of Validity Face validity Content validity Criterion-Related Validity Predictive Validity Construct Validity Discriminant Validity All types of validity are related.
4/25/2015Marketing Research11 Reliability and Validity Illustrated Situation 1: A lack of reliability my scale varies a lot (150, 160, 170) Situation 2: High reliability, but lacks validity My scale always shows 160, but other scales are different Situation 3: Reliable, consistent, and valid ALL scales show a consistent 160
4/25/2015Marketing Research12 Scaling Scaling Defined In order to decrease noise: you measure something several times Unidimensional scaling Multidimensional scaling Graphic Rating Scales Present to respondents with a graphic continuum typically anchored by two extremes