1. Determining Scale of Measurement 3 steps Examples Try a few

2. Scales (levels) of Measurement To determine level of measurement Step #1Identify the Unit of Observation (obs unit) (sampling unit) –(one of something) What you are interested on studying? Usually the individual (participant) for psychologists Other possible Observational units: –A rat –A Group/team –A Household –A City –A Country –A College student

3. Scales (Levels) of Measurement To determine level of measurement Step #2 Ask: “What am going to do with the Obs unit?” –Two options: Option A: Assign the Obs unit to a category (quality) –E.g. gender, race, social security number (unique) Option B: Measure the Obs unit on some attribute or behavior –Intelligence, age, motivational level, number of hotdogs eaten –If “Yes” to Option A Ask: are the categories ranked on some quality? –E.g. job class (clerical I, II, III) –E.g. class standing (rank in class) If “NO”, not ranked, then level of measurement is NOMINAL If “Yes”, categories ranked, level of measure is ORDINAL

4. Scales (Levels) of Measurement To determine level of measurement If Option B: Measure Obs Unit on some attribute or behavior Step #3 Identify Unit of Measure (Measurement Unit) –One of something (attribute or behavior) E.g. item on a test, inventory –Ask: “Does the measure have a true zero? Usually: Physical and behavioral ones do –E.g height, weight, number of cases sold Psychological attributes do not –IQ, need for approval, depression level, attitude toward boss

5. Scales (Levels) of Measurement To determine level of measurement If answer to “Does the measure have a true zero?” –Is “YES”, level is Ratio –Is “No”, level is Interval Try out a few:

6. What level (scale)? Number of children aboard each of 15 school buses? Observational unit? –One school bus Place bus in category? –No Measurement Unit? –One student Absolute zero? –Yes, bus could carry no students Level of measure? –Ratio

7. What Level Measurement? Students Fail v. Pass Observational unit? –One student Place student in category? –Yes: fail or pass Are the categories ranked on some quality? –no Level of measurement? –Ratio –Just kidding! –Nominal