Collection of Primary Data
Five Steps • Who are the subjects? Who (or what) do you need to get your data from? • Choose appropriate Data Collection Method • Decide how much data you require • Determine sampling methodology • Be aware and be able to describe why the choices you have made, might impact on the data you collect?
Step 1 • Who are the subjects? Who (or what) do you need to get your data from? • Are your subjects people – The general population • E.g. Customers, patients etc
– Experts • Knowledgeable within a particular subject area
• Other • E.g. Machines, products etc
Step 2 • Choose appropriate Data Collection Method – Interview – Focus group – Questionnaire – Observation – Reworking of collected data – Experiment • Measuring results • Control group
Step 3 • Decide how much data you require – Census – Sample • Not too big/not too small • Ideal sample size – Based on population size – Do you know this or can you estimate/guesstimate this?
• Calculate ideal sample size - on-line sample size calculator • Limitations – time etc.
– Vox Pop • Snapshot that only gives a ‘flavour’ of popular opinion
Step 4 • Determine sampling methodology – Best ones are ‘random’ • Problem - Need a ‘sample frame’
– Other none random methods – Most likely method for you – convenience sampling
Step 5 • Be aware and be able to describe why the choices you have made, might impact on the data you collect? – Bias – distortion in the data collected or a statistical result calculated from this data – Can result from • • • •
Inappropriate Data Collection Method Sample size too small Sampling methodology Other