Answering a single question
The simplest application of statistics is to answer a single question in the context of some practical subject area. For example,
Answering the question involves the following steps.
Statistics has a role to play in all stages of this process.
Feedback
The simple process outlined above is appropriate for some problems where data collection takes a long time and cannot be repeated. For example, it often takes over a year to conduct agricultural experiments — researchers only have a single opportunity to do their data collection, so they had better get everything right first time!
In most situations, the initial question is less well defined and a single pass through the process is not enough. The information obtained from the initial data generate further questions and we need to collect more data to help answer them.
Pilot studies
Feedback is often designed into the statistical process. For example, sometimes a small fraction of the data is initially collected and analysed. The information obtained from this pilot study is used to refine the data collection process. For example,
The pilot study can also provide information about how much data must be collected to give the desired accuracy in the main part of the study.
Unexpected results
Another example of feedback in the statistical process occurs when the initial analysis reveals unusual or unexpected features in the data. Such features may suggest further questions and therefore further data collection.