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Published on: July 3, 2020
Optimal design for estimating parameters of the 4-parameter hill model.
Leonid A Khinkis1, Laurence Levasseur, Hélène Faessel
1Department of Mathematics and Statistics, Canisius College, Buffalo, NY, U.S.A.;
Nonlinearity in Biology, Toxicology, Medicine
|March 31, 2009
Summary
D-optimal designs are robust experimental tools for estimating parameters in nonlinear sigmoid models like the Hill model. They offer practical advantages for planning experiments, especially when resources are limited.
Area of Science:
- Pharmacology
- Biostatistics
- Experimental Design
Background:
- Drug concentration-effect relationships often follow nonlinear sigmoid models.
- The 4-parameter Hill model is frequently used to describe these relationships.
- Accurate parameter estimation is crucial for model validity.
Purpose of the Study:
- Investigate the properties of D-optimal designs for parameter estimation in sigmoid models.
- Evaluate the robustness and efficiency of D-optimal designs.
- Compare different D-optimal design strategies.
Main Methods:
- Utilized D-optimal designs, which minimize the volume of confidence regions for parameter estimates.
- Assumed variance of random error proportional to a power of the response.
- Introduced a five-point design to enhance robustness and characterize the Hill curve's middle section.
- Compared four-point D-optimal designs with five-point and log-spread designs.
Main Results:
- D-optimal designs demonstrate robustness, yielding satisfactory results even with imprecise parameter estimates.
- A five-point design improved robustness and characterization of the Hill curve.
- Theoretical and practical comparisons showed D-optimal designs to be effective.
Conclusions:
- D-optimal designs are practical and valuable for planning laboratory experiments, particularly when the model is known, prior parameter knowledge is good, and experimental units are costly.
- This study aims to enhance practitioner understanding of D-optimal designs for routine experimental planning.
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