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Evaluating Survey Evidence: A Tale of Two Surveys. By: Brian Blake, Ph.D. Jennifer Vedder Erin Sonenstein Consumer-Industrial Research Program Cleveland State University Vanguard Conference National College of Natural Medicine Portland, Oregon January 11, 2011.
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Evaluating Survey Evidence:A Tale of Two Surveys By: Brian Blake, Ph.D. Jennifer Vedder Erin Sonenstein Consumer-Industrial Research Program Cleveland State University Vanguard Conference National College of Natural Medicine Portland, Oregon January 11, 2011
“A survey usually raises more questions than it answers!” “Be careful that a survey doesn’t lead you in a wrong direction!” Too often we hear…
Too little do we listen… “A goal without a plan is just a wish.” - A. Saint-Exupery, 1900-1944 “You designed this research backwards!!!”
Five Key Questions • Are we listening to the right people? • Are we listening to enough of the right people? • Can we trust what they say? • Do we understand what they tell us? • Does the information provide guidance for action?
Two Study Designs “Gen-Pop” ND Survey
“Gen-Pop” • Descriptive and Prescriptive Online survey of Oregon residents to: • Identify the public’sfamiliarity with NDs • Gauge the public’s image of NDs relative to other health care providers (HCPs), broadly defined • Unearth the distinct segments that compose the Oregon population, the segments being sectors that differ in regard to their orientations toward medical care • Estimate the demand for naturopathic medicine (NM) and how it changes from one segment to another • Calculate the “targetability” of each segment, i.e., the relative contribution of each segment to the spread of NM in Oregon • Devise a marketing/communication/service distribution strategy based on the above to increase usage of NDs and NM care in Oregon.
“Gen-Pop” • Discover parameters that can be effectively brought to the attention of Oregon legislators and health insurance carriers that can provide a rough gauge of: • Unmet health care needs in Oregon • Public satisfaction and particular difficulties experienced with health care coverage • Readiness to turn to NDs as a Primary Care Physician
ND Survey Mainly Descriptive Online survey of the nation’s ND community to: • Profile the ND community in America in regard to a variety of parameters: • Engagement in particular professional activities • Professional goals and interests • Provision of alternative treatment modalities • Form of reimbursement • Involvement in a primary care role • Reliance upon various forms of medications in prescriptions • Income from NM and other income streams • Demographic characteristics • Licensures and certifications beyond the ND
ND Survey • Chart the diversity of NDs in the above regards and identify sectors or “types” of NDs that compose the contemporary ND community in America. • Assess the needs and priorities of each ND type/sector in order to learn how to serve their distinct interests. • Identify graduates of ND programs who are not presently involved in NM. Who are they? Why are they no longer active? • In conjunction with information from the Oregon General Population survey explore the viability of mutually beneficial referral networks with non-ND healthcare providers.
Five Key Questions • Are we listening to the right people? • Are we listening to enough of the right people? • Can we trust what they say? • Do we understand what they tell us? • Does the information provide guidance for action?
Q1: Are we listening to the right people? • “Right people” = Representative sample of population • So, how do we obtain a representative sample? • Six steps to a representative sample…
For a representative sample… • Specify population clearly. Who is in? Who is out? • Gen-Pop… adults (+18 years old) in Oregon who have received care from a health care provider in the previous 2 years (from January 1, 2009) • ND Survey… persons who graduated in the past ten years (since 2001) with an ND degree from an accredited US college and/or who are current members of the American Association of Naturopathic Physicians (AANP) or a state level ND organization (e.g., OANP). Does not include current students working toward an ND degree. Includes ND degree holders not presently active in NM
For a representative sample… • Devise the “sampling frame,” a population listing with reasonable coverage current and is error free • Gen-Pop - members of an online panel residing in Oregon previously screened for age and medical care based on vendor records and confirmed by questions in survey. Like e-Rewards • Evaluation - practical, not perfect - coverage OK, but suspect - current and clean • ND Survey - listing of alumni records of five major ND colleges in US, membership list of AANP, membership listing of all state level ND organizations, compiled-cleaned by HRI
For a representative sample… 3. Draw probability sample Here a “stratified random sample” • Gen-Pop - sample proportionate to population of Oregon counties (most recent US Census estimate) • ND Survey - sample drawn proportionate to the ND population in each of 50 states (% calculated from sampling frame)
For a representative sample… 4. Design to obtain a high response rate Dillman review Finding in ancient crypt High rate essentials
For a representative sample… 5. Design so that subsample weighting of obtained data is possible • Gen-Pop - double weighting • by county to make data set proportional to county’s population (Census based) • by those few demographics (e.g., age) empirically shown in study to be predictive of readiness to see an ND (Census based) • ND Survey - single weighting • by state (based on percent of sample frame)
Five Key Questions • Are we listening to the right people? • Are we listening to enough of the right people? • Can we trust what they say? • Do we understand what they tell us? • Does the information provide guidance for action?
Q2: Are we listening to enough of the right people? • Standard formulae based on: • desired precision, e.g., ±3%, ±2% band • desired level of confidence that population characteristic is within band, often 95% • variability in characteristic of interest • more variability, larger sample needed • typically assume maximum • population vs. sector • number/size of subpopulations to be analyzed “stand alone,” males vs. females • projected response rate, e.g., if project 50% response, send out double needed sample size
B. Gen-Pop • Given: population =3.8 million (adjusted from 3,421,399) qualified (had care) = 70%, response rate = 20% variability = pop. max (50-50), seg mod (70-30) For OR whole need 600 precision = +/- 4% confidence = 95% send out = 3,000 • For typical (of 5) segment with average 150 per segment precision = =/- 7% confidence = 95% send out = 3750
C. ND Survey • Given: • For population (US) as a whole = 6,000, response= 50%, 90% qualify • Variability = pop max (50-50), seg mod (70-30) precision = ±3% confidence = 95% • For typical (of 5) segment precision = ±6% confidence = 90%
D. Recommend • Gen-Pop need 750 (assuming 5 segments) send out 3750 (assuming 20% response) possible “booster” sample if familiarity with NDs low • ND Survey needed - 750 send out - 1,500
Five Key Questions • Are we listening to the right people? • Are we listening to enough of the right people? • Can we trust what they say? • Do we understand what they tell us? • Does the information provide guidance for action?
Q3: Can we trust what they say? • Eliminate “bad respondents,” for example • overstatements • suspicious patterns of answers • Eliminate bad items for “illogical” answers based on relationships (correlations) among items • For Gen-Pop • health care provider (HCP) familiarity with licensed phentologist • What they say versus what they do. Stated Impact vs. Predicted Impact for HCP characteristics
Q3: Can we trust what they say? • Evaluation • Minimal checks for ND • Practical approach for Gen-Pop
Five Key Questions • Are we listening to the right people? • Are we listening to enough of the right people? • Can we trust what they say? • Do we understand what they tell us? • Does the information provide guidance for action?
Q4: Do we understand what they tell us? • How to interpret a given question • e.g., suppose numerous NDs say they place high priority upon time to educating the public about health care issues? • Why do so? Good for business? Desire to advance NM care? Enjoy being in limelight? • Use of mathematically derived dimensions that “look underneath” overt answers in both Gen-Pop and ND Surveys • Example of dimensions in image of NDs and other HCPs in Gen-Pop • First, the HCPs considered • Second, the characteristics • Then, the dimensions
HCPs Included • A conventional medical doctor (MD degree) • Naturopathic doctor (ND degree) • Licensed physicians assistant (PA) for primary care • Licensed practical nurse/licensed nurse practitioner/registered nurse for primary care • Licensed midwife/Dula • Psychiatrist (MD) • Psychologist (PhD/PsyD) or other licensed mental health professional • Chiropractor (DC degree) • Physical therapist (PT degree) • Certified massage therapist • Licensed acupuncturist • Registered dietician • Yoga, other mediation/controlled movement trainer
How well are particular HCPs described by each characteristic? (Scale 1-5)