Community Assessment Handout 4: Developing a Survey Characteristics of a good Survey Valid – accurately measuring the concept or idea that you want to measure. Reliable – yielding consistent results over time when used the same way with similar respondents. Culturally appropriate – being appropriate for the target population in terms of language, measurement approach, and questions asked. o Minimize response options (using 2 response options vs. 4 response options: “Agree” or “Disagree” vs. “Strongly Agree”, Agree”, “Disagree”, or “Strongly Disagree”) o Negative vs. positively framed item stems (“Not eating fruits is unhealthy” vs. “Eating fruit is healthy”) Focused – addressing your specific questions and only including questions that are essential to know. 1 Community Assessment Handout #4 Steps to Consider When Developing a Survey Developing a survey requires careful planning. The following are important steps to address in survey development: 1. Purpose of the survey (Which health problem/behavior? Or a general assessment?) 2. Questions to include in a survey (Questions regarding factors associated with the health problem/behavior) ** Example: if focusing on obesity, survey should includes questions regarding physical activity, diet, parks in neighborhood, etc. 3. Review validated surveys to identify appropriate questions (See page 3 for websites with standardized surveys) ** 4. Adapt/Adopt questions and develop the survey ** 5. Pilot test the survey (Format/length of survey, response categories, understood as intended, etc.) 6. Also think about Survey Design: Method for Sample Selection & Survey Administration (See pages 4-7) ** Consider sample selection when addressing these issues 2 Community Assessment Handout #4 Adopting Questions from Organizations The following is a list of organizations that have websites with standardized questions that you can review and adapt for your own use. Using existing validated questions can save you time and cost, and will allow you to compare your results with findings from other surveys with similar questions. Centers for Disease Control and Prevention: http://wwwn.cdc.gov/qbank/QuestionTopic.aspx National Cancer Institute: GEM Database: http://www.gem-beta.org/public/MeasureList.aspx?cat=2 http://healthservices.cancer.gov/surveys/screening_rp/screening_rp_breast_cervical_inst.p df (Questions regarding physician attitude on breast and cervical cancer screening) Behavioral Risk Factor Surveillance System (BRFSS): http://apps.nccd.cdc.gov/BRFSSQuest/index.asp http://www.cdc.gov/brfss/questionnaires/english.htm California Health Interview Survey (CHIS): http://www.chis.ucla.edu/ US Census: http://www.census.gov/acs/www/Downloads/questionnaires/2012/Quest12.pdf National Health Interview Survey (NHIS): http://www.cdc.gov/nchs/nhis/quest_data_related_1997_forward.htm LA County Health Survey: http://publichealth.lacounty.gov/ha/hasurveyintro.htm 3 Community Assessment Handout #4 Sample Selection Methods Types of samples: Probability and Non-probability sample 1. Probability sampling (Representative samples) Probability samples are selected in such a way as to be representative of the population. They provide the most valid or credible results because they reflect the characteristics of the population from which they are selected (e.g., residents of a particular community, students at an elementary school, etc.). Probability Sample Methods Method Simple Random: Each individual in the population of interest has an equal likelihood of selection. Example Put names of all students in a hat, and then draw 200 students without replacement. Pros -Relatively easy -Highly representative if all subjects participate; the ideal Systematic Random: The selection of every Nth subject on a list or a sequence. Every 10th customer entering the store may be approached for a survey, or every 25th number in the phone book may be called. -More precise than simple random as more evenly spread over population Stratified Random: In the survey of college undergraduates, you may choose to draw 50 students from each of the freshman, sophomore, junior, and senior strata, instead of 200 students from the combined student population. Randomly select 5 classes of 40 students each. Each class is called a cluster of students. - Can ensure that specific groups are represented, even proportionally, in the sample(s) (e.g., by gender), by selecting individuals from strata list The population is divided into groups (strata) and the data is collected from the strata by simple random sampling. Cluster: A particular segment of the population is sampled using existing lists (e.g., District, Households, etc). 4 -Applicable where no complete list of units is available Cons -Not possible without complete list of population members -Time-scale may be too long -If list has periodic (e.g., repeated cycle) arrangement then sample collected may not be an accurate representation of the entire population -Need a list or mapping of population -More complex, requires greater effort than simple random. -Strata must be carefully defined. -Clusters may not be representative of whole population but may be too alike -Typically “requires” larger sample Community Assessment Handout #4 2. Non-probability Samples (Non-representative samples) As they are not truly representative, non-probability samples are less desirable than probability samples. However, a researcher may be unable to obtain a random or stratified sample, or it may be too expensive. A researcher may not care about generalizing to a larger population. The validity of nonprobability samples can be increased by trying to approximate random selection, and by eliminating as many sources of bias as possible. Non-probability Sample Methods Method Example Quota sample: To be sure of their Deliberately set the inclusion, a researcher proportions of levels within could set a quota of 50% the sample. Generally done males for the sample. to insure the inclusion of a particular segment of the population. The researcher sets a quota, independent of population characteristics. Purposive Sample: Purposefully choosing a Non-representative subset support group as a place to of some larger population. recruit participants. Constructed to serve a very specific need or purpose. A researcher may have a specific group in mind. Researcher will attempt to zero in on the target group, interviewing whoever is available. Snowball Sample: Find one member of a Subset of Purposive Sample. (hard-to-reach) group; Achieved by asking a interview him/her then ask participant to suggest interviewee about other someone else who might be individuals who may willing or appropriate for qualify as potential the study. participants. Convenience Sample: Conducting survey with A matter of taking what you friends or going to the park can get. Volunteers would and asking anyone to take constitute a convenience the survey. sample. Although selection may be unguided, it probably is not random. 5 Pros -Ensures selection of adequate numbers of subjects with appropriate characteristics Cons -Not possible to prove that the sample is representative of designated population -Ensures balance of group sizes when multiple groups are to be selected -Samples are not easily defensible as being representative of populations due to potential subjectivity of researcher -Possible to include members of groups where no lists or identifiable clusters even exist (e.g., drug abusers, criminals) -Quick & inexpensive -No way of knowing whether the sample is representative of the population - Sample will most likely not be representative of the population Community Assessment Handout #4 Definition: Sample: A subset of a population used to study the population as a whole. Stratum: A layer, in this case refers to a subpopulation or level within a population (pl.- strata). Quota : A proportional part or share, the share assigned to each in a division or to each member of a body. Non-probability samples are limited with regard to generalization. Because they do not truly represent a population, we cannot make valid inferences about the larger group from which they are drawn. Validity can be increased by approximating random selection as much as possible, and making every attempt to avoid introducing bias into sample selection. The best sampling is probability sampling, because it increases the likelihood of obtaining samples that are representative of the population. Sources: http://www.stat.wmich.edu/s216/book/node28.html http://psychology.ucdavis.edu/sommerb/sommerdemo/sampling/types.htm http://psychology.ucdavis.edu/rainbow/html/fact_sample.html http://staff.argyll.epsb.ca/jreed/math9/strand4/4106.htm Black, T. R. (1999). Doing quantitative research in the social sciences: An integrated approach to research design, measurement, and statistics. Thousand Oaks, CA: SAGE Publications, Inc. (p. 118) 6 Community Assessment Handout #4 Survey Methods Summary Sheet Method Face-to-face Strengths -Minimizes missing data -Does not require high level of literacy from respondent -Can record reasons & characteristics on non-consenters -Allows much flexibility in length of survey & style of questions Weaknesses -Expensive -Relatively time-consuming -Requires intensive interviewer training & monitoring throughout -Can be hard to prevent consultation with/interference from others Mailed Survey -Relatively inexpensive method data collection -Widely dispersed populations can be surveyed. -No interviewer training required -Data collection takes a long time -Relatively low response rates -Can result in higher amounts of missing data -High literacy level required -Reminders required to increase response rates -Suitable only for fairly short & straightforward surveys -No information on non-consenters Telephone Survey -Widely dispersed populations can be surveyed inexpensively & easily -Minimizes missing data -Relatively inexpensive data collection method - Relatively quick method of data collection -Can use open-ended questions - Can record reasons and characteristics on non-consenters -Does not require high level of literacy from respondent -Need to keep questions fairly short and only a limited number of response options -Can’t ask questions requiring visual cues -Requires interviewer training & monitoring throughout -Can be hard to prevent consultation with/interference from others -Land phone line generally required -Limits sample due to cell phone prevalence Online/Computer Survey -Can be relatively inexpensive once initial costs have been overcome. -Relatively quick method of data collection -No interviewer training required -Can use questions requiring visual cues -Minimizes missing data -Maximizes data quality -Useful only for relatively large-scale surveys -High literacy level required -Basic computer skills required from respondents -Limits sample due to requirement of computer/online access 7 Community Assessment Handout #4 Adapted from Source: Newell, S. Perkins, J., Bowman, J.A. (1994). Accessing community samples: The pros & cons of different methods. Paper presented to Hunter Centre for Health Advancement Postgraduate Seminar, Newcastle, NSW. (Website: http://epubs.scu.edu.au/educ_pubs/203/) 8 Community Assessment Handout #4