Measurement Whats the difference between change and progress

Measurement

What’s the difference between change and progress? Progress requires measurement and comparison. What gets measured is what gets done. Unknown

“One true god rules at Google: data. The more you collect, the more you know and the more certain your decisions can be, disciples believe. ‘Often differences of opinion between smart people are differences of data, ’ says Marissa Mayer. ‘In some meetings people aren't allowed to say ‘I think …’ but instead must say ‘The data suggest …’” Marissa Mayer Former VP of Products, Google Current CEO of Yahoo

Definition of Terms • Measurement: Assigning a value to a variable. • Reliability: Consistency of measurement. • Validity: How meaningful, useful, and appropriate our conclusions are. – It is not a characteristic of a test per se, but rather our use of the results of the test.

Factors that Influence Reliability 1. What you measure – physical traits – cognitive traits – affective traits 2. The instrument you use 3. Your technique

1. What You Measure a. Physical Traits – most reliable of these three – e. g. , height, weight, blood pressure b. Cognitive Traits – less reliable than physical traits – e. g. , SAT questions c. Affective Traits – least reliable of these three – e. g. , feelings, attitudes, opinions

2. The Instrument You Use Height-Weight Table Bioelectrical Impedance Skinfold Dual Energy X-ray Absorptiometry

3. Your Technique

Scales of Measurement • Nominal: Named categories - race, gender, religion • Ordinal: Ordered categories - race finish, grade level, SES, Likert scale • Interval: Equal intervals - temperature in ºF and ºC • Ratio: Equal intervals with absolute zero - height, weight, time, scores, income

Scales of Measurement: Practice 1 In an experiment to determine if antibiotics increase the final weight of cattle, the following were measured for each animal in the study: sex, initial weight, weight gain, grade of meat …where grade is recorded as (A, B, or C). The scale of measurement for these variable are: a) nominal, ratio, interval, nominal b) nominal, ratio, nominal c) nominal, ratio, ordinal d) ordinal, ratio, ordinal e) ordinal, ratio, nominal

Scales of Measurement: Practice 2 A study was conducted to measure the effect of smoking upon the birth weight of a baby. The following variables were measured for each woman in the study: smoker (y/n), birth weight, APGAR score, age The scale of measurement for these variables are: a) nominal, ratio, ratio b) ordinal, ratio, interval c) ordinal, ratio, ordinal, ratio d) nominal, ratio, ordinal, ratio e) ordinal, ratio, ordinal