Educational Resources for Students Professor David J. Demko, PhD AgeVenture News Service Return to STUDENT RESOURCES HOME PAGE. Key Terms in Social Research 01. Qualitative versus quantitative research Qualitative Research - data typically in narrative form; gathered by use of observations and interviews; results contextual - unique to individual and setting. Purpose is to construct concepts and theory. Quantitative research - data numerical; gathered by quantifying observations, administering tests and other instruments; results generalizable. Purpose is to test concepts and theory. 02. Measurement Measurement - assigning value (numbers) to observations based on indices of an operational definition. 03. Operational Definition Operational Definition - special use of a term that translates abstract meaning into observable behaviors called indices. 04. Variables Variable - a measured characteristic (operationally defined) that can assume various values or levels. Discrete variables - have only certain values (whole numbers for example). Continuous variables - can take any value (accuracy of measurement). 05. Constants Constant - has only a single value. A certain characteristic (like grade level) can be a variable in one study and a constant in another study. 06. Scales of measurement Nominal scale - naming, used to label, classify, or categorize data (gender, SSN, number on athletic jersey, locker number, address). Ordinal scale - classification function plus observations are ordered, distance between adjacent values not necessarily the same (olympic medals, finishing place in a race, class rank). Interval scale - classification, ordered plus equal intervals between adjacent units (all test scores are assumed to be at the interval scale, temperature Fahrenheit, temperature Centigrade). Ratio scale - all of the above plus the scale has an absolute zero, a meaningful zero. Most physical measures are at the ratio level of measurement (height, weight, distance, time, pressure, temperature on the Kelvin scale - absolute zero is -273 degrees Centigrade). 07. Descriptive and inferential statistics Descriptive statistics are a way of summarizing data - letting one number stand for a group of numbers, can also use tables and graphs to summarize data. Inferential statistics - research statistics, a measure of the confidence we can have in our descriptive statistics, the statistics we use to test hypothesis. 08. Parametric and nonparametric statistics Parametric statistics - used with interval and ratio data and usually with data that were obtained from groups randomly assigned, normally distributed, and with equal variability between groups - preferred statistics to use, they are more "powerful" than nonparametic statistics. Examples we will study are t-tests, analysis of variance, and Pearson correlation coefficient. Nonparametric statistics - used with nominal and ordinal data and sometimes with interval and ratio data when other assumptions can not be met. Examples we will study are the chi-square test and the Spearman rank difference correlation coefficient. 09. Tests: Reliability and Validity Statistics Describe Effectiveness Reliability - a statistic used to determine the consistency of a test. Does the test measure the variables under study in the same way each time? Validity - a statistic used to determine the accuracy of a test. Does the test measure the variable that it is supposed to measure? 10. Tests: Norm-Referenced (NR) versus Criterion-Referenced (CR) NR Tests - used to compare the performance (behavior) of each test-taker to all other test takers. All performances (scores) are compared to the relative mean (average) of all scores. CR Tests - used to compare the performance (behavior) of each test-taker to an established standard. All performances (scores) are compared to an absolute scale. RETURN TO TOP OF THIS PAGE