Reliability

REL IABI LITY Reliability is concerned with how consistently the measurement technique measures the concept of interest.

Types of Reliability • Stability – concerned with the consistency of repeated measures or test-retest reliability. • Equivalence – focused on comparing twp versions of the same instrument (alternate forms reliability) or two observers (interrater reliability) measuring the same event. • Homogeneity – addresses the correlation of various items within the instrument or internal consistency; determined by splithalf reliability or Cronbach’s alpha coefficient.

VAL IDI TY The extent to which an instrument reflects the concept being examined.

DI MENS IONS OF DA TA COL LECTION APPROAC HES

Data collection methods vary along four important dimensions: • Structure • Quantifiability • Researcher Obtrusiveness • Objectivity

MAJOR TYPES OF DA TA COL LECTI ON MET HOD S • Self-Reports • Observation • Biophysiologic Measures

Self-Reports • Unstructured Self Reports

- completely unstructured interview -

Focused interview focus group interview life histories Critical Incidents Diaries

Interviews • Unstructured Interviews • Structured Interviews - describing interview questions -

pretesting the interview protocol training interviewers preparing for an interview Recording interview data

QUESTIONNAIRES Collecting questionnaire data:  Clarity Brevity Simplicity Applicability

Scales • Rating Scales • Likert Scales • Semantic Differentials • Visual analog scales

Developing a Data Collection Plan • • • •

Identify data needs Select type of measures Select and develop instruments Pretest the data collection package • Develop data collection forms and procedures

Implement Data Collection Plan • Select research personnel • Train data collectors