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Optimal sample sizes for precise interval estimation of Welch's procedure under various allocation and cost
1Department of Management Science, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30050. gwshieh@mail.nctu.edu.tw
Behavior Research Methods
|August 2, 2011
Summary
This study introduces optimized sample size methods for Welch's procedure, enhancing precise interval estimation for comparing two population means. These new approaches offer flexibility in allocation and cost, improving statistical practice.
Area of Science:
- Biostatistics
- Statistical Methods
Background:
- Welch's procedure is a robust alternative to the Student's t test for comparing means of normal populations with unequal variances.
- Confidence intervals are crucial for statistical practice, necessitating precise sample size determination.
Purpose of the Study:
- To develop exact sample size optimization methods for Welch's procedure.
- To enhance precise interval estimation for the difference between two means.
- To consider various allocation and cost constraints.
Main Methods:
- Exact approaches for sample size determination.
- Assessing confidence interval precision via expected half-width and assurance probability.
- Exploring design schemes including group size ratios, fixed sample sizes, cost-performance optimization, and minimum cost for specified precision.
Main Results:
- Proposed methods provide exact sample size calculations for Welch's procedure.
- Optimized designs address diverse allocation and cost considerations.
- Developed programs enhance existing statistical software capabilities.
Conclusions:
- The study offers improved sample size determination methods for Welch's procedure.
- These methods facilitate precise interval estimation under various practical constraints.
- The developed tools offer greater generality for statistical software users.
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