All Ireland Traveller Health Study Our Geels - Department of Health ...

Health Survey Findings
Analysis Strategy for
Technical Report 1
Data Cleaning and Preparation
The data was received from the field in a raw electronic format (SQL database), with the responses for
the census and all the surveys in one single database. The database also included files for a number of
interview outcomes, including refusals, unavailable or moved families. It was therefore necessary for the
questionnaire and database programmer to go through cleaning and restructuring at the level of the
SQL database. This was then followed by conversion to an SPSS database. The main tasks in the data
cleaning and preparation process were:
• Removal of duplicate and invalid files and addition of files that had not been uploaded but retrieved
from laptops that were returned from the field.
• Renaming and restructuring of variables into an analysable and interpretable format.
• Combining the proxy-answered variables of the adult Health Status and Service Utilisation Surveys
with their directly-answered counterparts.
• Creation of individual-level demographic data files from family level files that nested demographic
data for several individuals of the same family.
Because ROI data was received before the NI data, all the processes were initially carried out on the ROI
database. The data cleaning and transformation syntax generated was then customised to suit the NI
variables and any issues specific to the NI database, before it was run on the NI database.
Analysis
The analysis was carried out in 2 rounds. The first round ran in tandem with the data cleaning and
preparation process. ROI data was initially partitioned into the constituent census, child and adult
surveys. The study team data analysts attended a training session where the structure of the databases
and the questionnaire were explained. They were supplied with an analysis and reporting programme
prepared by the study’s information technology (IT) group. The programme produces standard reports
of census/survey response percentages as well as age and gender breakdown for the survey responses.
Each analyst had to customise the programme into a census- or survey-specific programme. They
received training on the process to operate their analysis, and all analysts submitted a complete report
including their analysis programmes once completed. Finalised census- and survey-specific analysis
programmes were then generated, including an adjusted version for the NI database. Finally, the
cleaned and finalised analysis syntaxes were rerun on the final databases, in a second round of analysis.
Respondents did not answer every question, which created a variation in the response rates across
the questions. Missing values were not inputted and the reported percentages are based only on
the number of people who responded to the question, excluding those who responded with ‘Don’t
know’ or ‘Refused’ as well as those who did not respond. That is there is a difference in the number of
response reported for each variable. For multiple response sets, the percentages were based on those
who selected at least one response, excluding those selecting ‘Don’t know’ or ‘Refused’ and those who
did not select any option. Furthermore, the total number of Travellers who responded to each subquestionnaire
is calculated from the maximal valid response to an item within that sub-questionnaire.
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