1. Educational Research: Competencies for Analysis and Application, 9 th edition. Gay, Mills, & Airasian © 2009 Pearson Education, Inc. All rights reserved. 1 Data Types Describe nominal, ordinal, interval, and ratio data types

2. Educational Research: Competencies for Analysis and Application, 9 th edition. Gay, Mills, & Airasian © 2009 Pearson Education, Inc. All rights reserved. 2 Measurement Scales Nominal variables describe categorical data. e.g., gender, political party affiliation, school attended, marital status Nominal variables are qualitative. Quantitative variables range on a continuum with ordinal, interval, and ratio variables.

3. Educational Research: Competencies for Analysis and Application, 9 th edition. Gay, Mills, & Airasian © 2009 Pearson Education, Inc. All rights reserved. 3 Measurement Scales Ordinal variables describe rank order with unequal units. e.g., order of finish, ranking of schools or groups as levels Interval variables describe equal intervals between values. e.g., achievement, attitude, test scores

4. Educational Research: Competencies for Analysis and Application, 9 th edition. Gay, Mills, & Airasian © 2009 Pearson Education, Inc. All rights reserved. 4 Measurement Scales Ratio variables describe all of the characteristics of the other levels but also include a true zero point. e.g., total number of correct items on a test, time, distance, weight