STATEMENT OF THE PROBLEM ANDSTUDY DESIGN

Lu Ann Aday, Ph.D.

The University of Texas

School of Public Health

TYPE OF DESIGN: Observational – Cross-Sectional (One-Group) GROUPS

No. of groups: 1 Criteria for selection: Population of

interest

TIME PERIODS No. of time periods: 1 Reference periods: Present (and recall of

past)

TYPE OF DESIGN: Observational –Group-Comparison (Case-control) GROUPS

No. of groups: 2+ Criteria for selection: Population subgroups

with and without characteristic of interest

TIME PERIODS No. of time periods: 1 Reference periods: Present and recall of

past

TYPE OF DESIGN: Observational –Longitudinal (Prospective) GROUPS

No. of groups: 1 or 2+ Criteria for selection: Population or

subgroups that are and are not likely to develop characteristic of interest

TIME PERIODS No. of time periods: 2+ Reference periods: Present and future

TYPE OF DESIGN: Experimental –“True” Experiment (Randomized Clinical Trial)

GROUPS No. of groups: 2+ Criteria for selection: Randomly

determined subgroups of population

TIME PERIODS No. of time periods: 2+ Reference periods: Present and future

DESIGN DIMENSIONS

HEALTH SURVEY EXAMPLES

UNICEF MULTIPLE INDICATOR CLUSTER SURVEYS (MICS)

CALIFORNIA HEALTH INTERVIEW SURVEY (CHIS)

NATIONAL DENTAL MALPRACTICE SURVEY(NDMS)

Study Objectives 1. To estimate and monitor World Summit for Children and related World Fit for the Millennium Development Goals (MDGs) indicators of child survival and development for children and mothers in participating countries.2. To compare the indicators over time, as well as across countries.

1. To provide statewide estimates for the population of the State of California overall and local-level estimates for most counties in the State of California on a variety of public health topics, e.g., health status, health care access, insurance coverage.2. To compare estimates across local areas and between larger racial/ ethnic groups, and selected smaller ethnic groups.

1. To estimate dental malpractice insurance experience in a representative sample of U.S. dentists in 1991.2. To test hypotheses regarding the practice characteristics that are predictive of dental malpractice insurance experience.

Study Designs Descriptive longitudinal, comparative national surveys conducted in 1995, 2000, & 2005 in participating countries

Descriptive longitudinal, comparative state & local surveys conducted on a biennial basis, beginning in 2001, in the State of California

Analytical cross-sectional national survey of U.S. dentists, conducted in 1991

Research Questions

What? World Summit for Children & MDG indicators of child survival & development

health status, chronic conditions, health behaviors, health care access, insurance coverage, etc.

malpractice insurance experience & practice characteristics

Who? children & mothers state & county populations dentists

Where? participating countries State of California U.S.

When? 1995, 2000, 2005 2001, 2003, 2005 1991

Why? -- -- To test hypotheses regarding the practice characteristics that are predictive of dental malpractice insurance experience.

SAMPLE OBJECTIVE: Objective 1

1. TO ESTIMATE dental malpractice insurance experience in a representative sample of dentists in the U.S. in 1991.

SAMPLE OBJECTIVE: Cross-Sectional, Descriptive Design

OBJECTIVE ELEMENTSTO ESTIMATE STATISTICAL PROCEDURES:

Univariate, e.g., frequencies,

mode, median, mean

dental malpractice insurance experience WHAT?

in a representative sample of dentists WHO?

in the U.S. WHERE?

in 1991. WHEN?

SAMPLE OBJECTIVE: Objective 2

2. TO COMPARE dental malpractice insurance experience by the dentist’s demographic characteristics.

SAMPLE OBJECTIVE: Group-Comparison, Descriptive Design

OBJECTIVE ELEMENTSTO COMPARE STATISTICAL PROCEDURES:

Bivariate, e.g., chi-square, t-test, ANOVA, correlations

dental malpractice insurance experience WHAT? (dependent variable)

by the dentist’s demographic characteristics.

WHO? (one independent variable)

SAMPLE OBJECTIVE: Objective 3 3. TO ANALYZE the relative

importance of doctor-patient communication, practice characteristics, practice finances, and dentist’s demographic characteristics in predicting dental malpractice insurance experience.

SAMPLE OBJECTIVE: Objective 3—Hypothesis Doctor-patient communication is

more important than practice characteristics, practice finances, and dentist’s demographic characteristics in predicting dental malpractice insurance experience.

SAMPLE OBJECTIVE: Cross-Sectional, Analytical Design

OBJECTIVE ELEMENTSTO ANALYZE the relative importance of STATISTICAL PROCEDURES:

Multivariate, e.g., linear regression, logistic regression

• doctor-patient communication• practice characteristics• practice finances, and• dentist’s demographic characteristicsin predicting

WHO? (two or more independent/control variables)

WHY? (hypothesis re results)

dental malpractice insurance experience. WHAT? (dependent variable)

MEASUREMENT MATRIX:

National Dental Malpractice Survey (Aday & Cornelius, 2006, Table 15.1)

QUESTION CONCEPT LEVEL OBJECTIVE

3 Doctor-patient communication: characteristics of unsatisfactory patient encounters (Likert scale)

ordinal(interval)

3

10 Practice characteristics: avg. office waiting time for patient

ordinal 3

28 Practice finances: % patients with insurance coverage

interval 3

35 Malpractice insurance: no. of complaints

ordinal 1, 2, 3

54 Demographics: gender nominal 2, 3

SURVEY ERRORS: Matching the Survey Design to Survey Objectives

Systematic Errors Variable Errors

Poor internal validity

Poor external validity

Design specification ambiguity

Solutions to errors Use randomization, matching, or statistical controls to rule out other factors that may account for relationships between variables.

Clearly specify where, with whom and when the survey will be done in stating the study objectives and design the sample frame and survey sampling procedures accordingly.

Clearly specify the study objectives and related concepts to be measured in the survey, particularly in relationship to the underlying study design and data analysis plan for the study.