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The Art and Science of formulating and asking survey questions of Mexican Migrants: overview of surveys and their use in public health. MarÃa Luisa Zúñiga, Ph.D. Associate Professor UCSD Division of Global Public Health Mexican Migration Field Training Program Week Thursday October 6, 2011.
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The Art and Science of formulating and asking survey questions of Mexican Migrants: overview of surveys and their use in public health María Luisa Zúñiga, Ph.D. Associate Professor UCSD Division of Global Public Health Mexican Migration Field Training Program Week Thursday October 6, 2011
learning objectives Students should be able to describe: • How surveys are used in public health • How do you know if a survey is any good? • Examples of validated survey measures
How are surveys used in public health? Surveys can be used to: • help answer research questions • Guide decisionmaking (e.g. where to use resources) • Guide clinical care (e.g. measure perceived improvement in health) • Better understand a health problem
Elements of a survey • A survey can be comprised of different parts that attempt to understand a specific phenomenon (e.g. depression) • May be broken down into different sections (e.g. demographic, specific risk behaviors, deportation experience, etc.)
Surveys allow you to measure • Outcomes (a.k.a dependent variables) an outcome should help you answer your research question (e.g. frequency and type of depression from which migrants suffer) • Predictors/indicators (a.k.a. independent variables) Questions or measures that we hypothesize may be associated with, contribute to or cause the outcome • Co-variates: information that may help explain or contextualize the phenomenon (gender, age, educational attainment)—can be a predictor
A survey and the type of analysis you conduct will be matched with the study design • Crossectional study – measure a health issue at a point in time • Longitudinal study • In what ways might a survey differ depending on the type of study?
What does it mean if a survey is generalizable? • The extent to which the survey produces findings and conclusions based on a sample population that can be applied to broader populations– may also apply to a specific population such as populations that migrate….HOWEVER… Ref: http://writing.colostate.edu/guides/research/glossary/
What does it mean if a survey has good internal consistency (I.C.)? • Survey I.C. indicates the degree to which a group of survey questions (a construct) that have been chosen to measure a specific characteristic, skill, or quality are actually allowing you to measure it. Different questions can allow you to make sure you have accurately captured or assessed an issue versus one question—why is asking one question about an issue not as strong an indicator of it?
What does it mean if a survey has good internal consistency (I.C.)? I.C. is measured mathmatically using approaches such as Factor Analysis (one common measure of I.C. is called Chronbach’s alpha) • High internal consistency means that the questions are closely related as a group or ‘construct’ and are mathematically ‘hanging together’ to help the researcher get at the phenomenon he/she wants to measure
Survey Reliability • A survey is ‘reliable’ if you can use it in populations with similar characteristics and it will tend to elicit similar responses
The World Mental Health Composite International Diagnostic Interview (CIDI) Borges_CrossNationalStudyMexUSMigrationSubstUseSubsDisorder_2011_DrugandAlcoholDependence Breslau_MigrationfromMexicotoUS&SubsequentRisk for Depressive &Anxiety_2011_ArchGenPsychiatry Breslau et al. 2007_Psychiatry Research_Mental disorders among Mexican immigrants vs natl sample of Mexicans