Unit 4 sec 1.2

Unit 4 sec 1.2 The statistical investigation cycle

17 November 2015

22:57

As it was mentioned in the introduction to this unit, there are 4 clearly identifiably for stages in most statistical

investigations, which can be summarised as follows

the 4 stages of a statistical investigation are.

Stage 1 Pose a question.

Stage 2 collect relevant data

Stage 3 Analyse the data

Stage 4 Interpret the results

It may be helpful to think of these stages set out as a cycle, the PCAI cycle. Here the problem starts in the real world and is resolved by making the journey into the statistical world and back again.

Note that it is important to be as specific as possible posing a statistical question. The better the investigation can be attuned to the question, and the ‘the chance of obtaining a useful answer. The less focused the question, the wider the investigation and the greater the chance that nothing very informative will come out of it.

Not surprisingly, different statistical techniques applied to different stages of the statistical modelling cycle.

Ø P: pausing a clear question should normally be the 1^st stage of any statistical work. The decision as to which techniques are to be used subsequently will depend on the sort of question that has been asked at the start of the investigation.

Ø C: collecting relevant data will involve issues such as choosing samples and designing questionnaires.

Ø  A: this stage, analyzing the data is where techniques like calculating averages and plotting graphs and charts will take place.

Ø  I: the final stage, interpreting the results, take the action back to the original context from which the initial question was posed. Do the data analyses how to answer the original question? If “yes” then you can stop, there. If “no”, then you may need to travel around the cycle once again, perhaps this time with a slightly modified question using different analytical techniques.

The 1^st was the categorization of statistical investigations into 3 types: summarizing, comparing or seeking a relationship.

 2^nd, the PCAI statistical

investigation cycle was introduced. This cycle, which may be gone around more than once, consists of 4 stages, pausing a question (P), collecting relevant data (C), analyzing data (A) and interpreting the result (I).