Lecture 1 Introduction to course Introduction to measurement

Pre-requisite (or co-requisite) or permission of instructor

Format Lectures Guest lectures Small group discussions/presentations –group and room assignments to be posted on web-page Information on web-page –Detailed schedule on web-page –Course objectives on web-page

Web-page Detailed schedule Course objectives Lectures Small group exercises –guidelines –group assignments Assignments Other?

Readings Course packs: –1) required readings –2 additional readings –more to come! Available at Copies Nova –(corner of Sherbrook and Peel)

Assessment Assignments (20%) –4, graded by TA Paper critiques (10%) –5–5 To be posted on web-page with due date Work handed in late will not be accepted!

Assessment (cont) Mid-term exam (30%) –Monday Nov 10, 11: :30 Final exam (40%) –Monday Dec 15, 9: :00

Introduction to measurement Purposes of measurement Types and sources of data Types of variables Questionnaires Types of scale

Purposes of measurement Clinical –screening, diagnosis, monitoring in individuals Surveillance –planning and monitoring public health and health care in populations Research –measurement of determinants, outcomes, confounders/modifiers

Examples of requirements by purpose of measurement Clinical –discrimination between health and disease relevant to management Surveillance –valid measurement of trends Research –maximize validity of study results

Sources of data Primary vs secondary Clinical observations Questionnaires and interviews Reportable diseases and registries Health records Administrative databases (hospital discharges, claims, medication prescription) Vital statistics

Examples of measures: for discussion Use of health services during past year (doctor visits, hospitalization) Use of alcohol and drugs (current and lifetime) Blood pressure (current and during past 5 years) Mood/depression (current and lifetime)

Types of variables (level of measurement) Continuous (syn. dimensional, quantitative, interval) Categorical (discrete) –dichotomous, binary –polychotomous nominal ordinal

What level of measurement? Country of birth Blood pressure Diagnosis of SARS Level of pain

Planning questionnaires Open-ended or close-ended Level of measurement Choice of response scale

Open-ended question

Question wording: Open- vs close-ended questions Close-ended questions –used most frequently –easier to analyze Open-ended questions –useful in exploratory research –basis for developing more structured questions in later research –analysis more time-consuming, requires qualitative methods

Alternative formats

Nominal scale

Ordinal scales

Disadvantages of categorical scales Loss of information Loss of precision

Continuous response scales in questionnaires Visual analogue scale Adjectival scale Likert scale Semantic differential scale

Visual analogue scale

Likert scale