SADC Course in Statistics

“To the Woods” discussion

(Sessions 10)

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Learning Objectives

By the end of this session, you will be able to

• discuss the gains in precision with stratification compared to simple random sampling and the circumstances under which such gains can be expected

• have an appreciation of the correct computation of a ratio estimate

• recognise why estimating a ratio is different from estimating a proportion

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Session contents

• Discussion of results from the “To the Woods” exercise using a selected data set

• Post-stratification – can this be done if scheme A had been adopted? How?

• Revision of ideas of simple and stratified random sampling

• Discussion of how ratio estimates may be calculated and how they differ from estimating population proportions based on a fixed sample size.

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Post-stratification: exercise

• In small groups, there will be a discussion of ways in which results from Scheme A can be used to improve the estimation

• You will then attempt to produce such estimates and compare it with previous results of Scheme A.

• A discussion will follow.

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