An introduction to statistics

Article 4. An introduction to estimation—1. Starting from Z

P Driscoll, F Lecky, M Crosby

Accident and Emergency Department, Hope Hospital, Salford M6 8HD, UK

Correspondence to:
Correspondence to: Mr Driscoll, Consultant in A&E Medicine (pdriscoll@hope.srht.nwest.nhs.uk)

• Estimating an element from a population with known standard deviation
  
• Estimating a statistic from a population with known standard deviation
  

In covering these objectives we will introduce the following terms:

• Standard normal distribution
  
• z statistic
  
• Confidence intervals
  

In the previous article the term inferential statistic was introduced.¹ This form of numeric manipulation is often used to estimate a population's parameter from a sample's statistic. For example, inferential statistics would be used to estimate a population's mean from a sample's mean. It can also be used to do the opposite—that is, estimate a sample statistic from a population's parameter. This is not commonly done because it requires the population's mean and standard deviation to be known and this is rarely the case.

In both calculations the values obtained are only estimations because of the normal variation that occurs. We can however work out the probability of a particular value based upon . . . [Full text of this article]

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This article has been cited by other articles:

• Driscoll, P, Lecky, F (2001). Article 7. An introduction to hypothesis testing. Parametric comparison of two groups--2. Emerg. Med. J. 18: 214-221 [Full Text]  
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• Driscoll, P, Lecky, F (2001). Article 5. An introduction to estimation--2: from z to t. Emerg. Med. J. 18: 65-70 [Full Text]