Data Collection Methods Mrunalini JS

2 ‘It is a capital mistake to theorize before one has data.’ -Sir Arthur Conan Doyle as Sherlock Holmes

Where do data come from? all nice and collated in a database – from: all nice and collated in a database – from: –Insurance companies (claims, medications, procedures, diagnoses, etc.) –Firms (demographic data, productivity data, etc.)

Where do data come from? Take a step back – if we’re starting from scratch, how do we collect / find data? Take a step back – if we’re starting from scratch, how do we collect / find data? –Secondary data –Primary data

5 Data Collection Options Data collection possibilities are wide and varied with any one method of collection not inherently better than any other Data collection possibilities are wide and varied with any one method of collection not inherently better than any other Each has pros and cons that must be weighed up in view of a rich and complex context Each has pros and cons that must be weighed up in view of a rich and complex context

6 The Data Collection Process All methods of collection require rigorous and systematic design and execution that includes All methods of collection require rigorous and systematic design and execution that includes –thorough planning –well considered development –effective piloting –weighed modification –deliberate implementation and execution –appropriate management and analysis

Secondary Data Secondary data – data someone else has collected Secondary data – data someone else has collected

Secondary Data – Examples of Sources County health departments County health departments Vital Statistics – birth, death certificates Vital Statistics – birth, death certificates Hospital, clinic, school nurse records Hospital, clinic, school nurse records Private and foundation databases Private and foundation databases City and county governments City and county governments Surveillance data from state government programs Surveillance data from state government programs Federal agency statistics - Census, NIH, etc. Federal agency statistics - Census, NIH, etc.

Secondary Data – Limitations What did you find on the frustrating side as you looked for data on the state’s websites? What did you find on the frustrating side as you looked for data on the state’s websites?

Secondary Data – Limitations When was it collected? For how long? When was it collected? For how long? –May be out of date for what has to be analyzed. –May not have been collected long enough for detecting trends. –E.g. Have new anticorruption laws impacted Russia’s government accountability ratings?

Secondary Data – Limitations Is the data set complete? Is the data set complete? –There may be missing information on some observations –Unless such missing information is caught and corrected for, analysis will be biased.

Secondary Data – Limitations Are there confounding problems? Are there confounding problems? –Sample selection bias? –Source choice bias? –In time series, did some observations drop out over time?

Secondary Data – Limitations Are the data consistent/reliable? Are the data consistent/reliable? –Did variables drop out over time? –Did variables change in definition over time? E.g. number of years of education versus highest degree obtained. E.g. number of years of education versus highest degree obtained.

Secondary Data – Limitations Is the information exactly what is needed? Is the information exactly what is needed? –In some cases, may have to use “proxy variables” – variables that may approximate something you really wanted to measure. Are they reliable? Is there correlation to what actually want to be measured? –E.g. gauging student interest in U.W. by their ranking on FAFSA – subject to gamesmanship.

Secondary Data – Advantages No need to reinvent the wheel. No need to reinvent the wheel. –If someone has already found the data, take advantage of it.

Secondary Data – Advantages It will save money. It will save money. –Even if have to pay for access, often it is cheaper in terms of money than collecting own data.

Secondary Data – Advantages It will save time. It will save time. –Primary data collection is very time consuming.

Secondary Data – Advantages It may be very accurate. It may be very accurate. –When especially a government agency has collected the data, incredible amounts of time and money went into it. It’s probably highly accurate.

Secondary Data – Advantages It has great exploratory value It has great exploratory value –Exploring research questions and formulating hypothesis to test.

Primary Data Primary data – data what researcher collects Primary data – data what researcher collects

Primary Data - Examples Surveys Surveys Focus groups Focus groups Questionnaires Questionnaires Personal interviews Personal interviews Experiments and observational study Experiments and observational study

Primary Data - Limitations Do need time and money for: Do need time and money for: –Designing collection instrument? –Selecting population or sample? –Pretesting/piloting the instrument to work out sources of bias? –Administration of the instrument? –Entry/collation of data?

Primary Data - Limitations Uniqueness Uniqueness –May not be able to compare to other populations

Primary Data - Limitations Researcher error Researcher error –Sample bias –Other confounding factors

Data collection choice What researcher must ask : What researcher must ask : –Will the data answer the research question?

Data collection choice To answer that To answer that – –must first decide what research question is – –Then need to decide what data/variables are needed to scientifically answer the question

Data collection choice If that data exist in secondary form, that can be used, keeping in mind limitations. If that data exist in secondary form, that can be used, keeping in mind limitations. But if it does not, and the researcher is able to fund primary collection, then it is the method of choice. But if it does not, and the researcher is able to fund primary collection, then it is the method of choice.

Combining Data Collection Methods Methods and instruments are often combined with one another. Methods and instruments are often combined with one another.

Triangulation Using a number of data collection methods is often called triangulation. Using a number of data collection methods is often called triangulation.