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Aims and Objectives. To understand the theory regarding sampling, and inferences to populationsTo evaluate the pros and cons of administration methodsWording of Questions and benchmarkingDetermining cause and effectAnalysing the survey dataTo consider the implications of these findings for your own research plans..
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1. Surveys, Questionnaire Design and Data Analysis. Dr Brendan Burchell
Faculty of Social and Political Sciences
Bb101@cam.ac.uk
Wednesday 26th March 2008
2. Aims and Objectives To understand the theory regarding sampling, and inferences to populations
To evaluate the pros and cons of administration methods
Wording of Questions and benchmarking
Determining cause and effect
Analysing the survey data
To consider the implications of these findings for your own research plans.
3. Sampling Theory As random samples increase in size, their properties resemble the population from which they are drawn more closely.
SE of sample mean = SD / SQRT N
Note
Only applies to random samples. Sample size cannot combat bias.
Size of population unimportant.
4. Methods of Administration Face-to-face
Time-consuming, costly?
Worse social desirability biases?
Post
Low response rate
Phone
Who are you talking to?
Internet?
Improving.
5. Is representative sampling Important? To make exact predictions about the nature of the population (e.g. to predict an election)
Essential
To explore the relationships between variables in a sample and generalise to a population
Desirable
To explore mechanisms, processes, qualitatively
?
6. Methods of selecting random samples 1 Random number tables to select from populations
2 Random numbers and constant intervals
(full list of population necessary)
3 Random numbers and procedures to infill gaps in population lists
Stratified Samples (boosting small groups?)
7. Multi-Stage Sampling Eg. sampling to select organisations,
then workplaces,
then individuals
Weighting may be necessary to re-adjust sample to be representative of population
8. Other Sampling Methods Telephone “random digits”
Administrative lists
Emails / Web
Newspaper adverts
Snowballing
Theoretical Case-Studies
Outliers
9. Non-Response Reduced Sample Size
Increased Error
Costly, but no loss of representativeness
Increased Bias
Much more serious
10. Reducing Non-Response Appropriate methods of administration
E.g. face-to-face interviews
Call-Backs
Quality of postal questionnaire / covering letter
Prizes / Rewards
Relevance of topic
11. Question Wording Open Ended
What are the significant threats to Health and Safety involved in this process?________________
Closed Questions
Which of the following are significant threats to the Health and Safety of this process?
Human error, malfunction, fire, alcohol, inadequate training, operators falling asleep, earthquake, terrorism, faulty materials, employee sabotage, inadequate supervision, poor management, extreme weather, acts of god, computer errors, computer viruses, ……
12. What are you trying to find out? “Objective facts”.
How many days of manufacturing were lost last year due to equipment failure?
Who knows?
Can the results be verified?
Perceptions
How satisfied are you with the reliability of your equipment?
13. Open vs closed questions Open
Not constraining
Need less piloting
Get information “in their own words”
Closed
Less time-consuming to code
Can include “other, please specify”
Easier to lead?
14. Overcoming Social Desirability When did you last do a health and safety check?
We all know that if you completed health and safety checks as often as the rulebook says you should, you wouldn’t get anything else done. When did you last manage to do a health and safety check?
15. Pilot all questions Spot the error:
Do you work part time?
Qualitative pilots?
Quantitative pilots?
16. Who is the expert? You or the Participant? How long have you been doing this job?
How many errors have you made in the last month?
OR
Doing your job, does the number of errors you make decrease over time?
17. Resources Plagiarism of questions is a virtue!
See the Questionbank
http://qb.soc.surrey.ac.uk/
18. Analysing the data from a survey Specialist packages, eg Minitab, SPSS
Or Generic tools, eg MS Excel
Analyse the data in stages:
Look at questions individually, check for coding errors, initial conclusions. Graph data.
Start to look for evidence of differences between batches (i.e. relationships) by comparing means
Only then, perhaps, check for statistical significance.
19. Guiding Philosophies of Data Analysis Are you a Judge & Jury or a detective?
Explore all aspects of data
Not just Central Tendancy
Mean, Median, Mode
But Also
Spread
Shape
Outliers