Restricted Maximum Likelihood
Restricted Maximum Likelihood - Related Videos
09:45
Restriction Enzyme Digests
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2023
Restriction enzymes or endonucleases recognize and cut DNA at a specific sequence. These enzymes occur naturally in bacteria as a defense against bacteriophages - viruses that infect bacteria. Bacterial restriction enzymes cut the invading bacteriophage DNA while leaving the bacterial genomic DNA unharmed due to addition of methyl groups. This video explains the basic principles of restriction enzymes including: how restriction enzymes are named and the types of recognition sites and...
01:13
Maximum Deflection
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2024
When analyzing beams under unsymmetrical loads, such as a train moving on a bridge, it is crucial to accurately determine the points of maximum stress and deflection. The process involves identifying the maximum deflection of the beam, which may not always occur at its midpoint due to the uneven distribution of the load. The maximum deflection occurs at a specific point, known as point O, where the tangent to the deflection curve is horizontal. To find point O, the slope of the tangent at any...
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Maximum Power Transfer
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2024
Numerous practical applications within engineering disciplines, such as telecommunications, necessitate optimizing power delivery to a connected load. This pursuit, however, entails inherent internal losses, which can either equal or exceed the power supplied to the load. The Thevenin equivalent circuit is helpful in finding the maximum power a linear circuit can deliver to a load. It is assumed in this context that the load resistance can be adjusted. By substituting the entire circuit with...
01:12
Maximum Size of Aggregate
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2024
The maximum size of aggregate is defined as the aperture of the sieve retaining 15 percent or more of the particles present in the aggregate sample. The aggregate's maximum size impacts the concrete's water requirement, workability, and strength. Larger aggregates reduce the surface area needing cement paste coverage, which can lower water needs, thereby allowing a decrease in the water-to-cement ratio when the desired workability and richness of the mix are to be maintained, which can result...
13:24
DNA Isolation and Restriction Enzyme Analysis - Student Protocol
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2019
DNA Isolation ExpandNOTE: In this experiment you will perform DNA isolation under two experimental conditions: one using a buffer containing the detergent SDS and one without detergent. Hypotheses: The alternate hypothesis for this experiment might be that the sample prepared without SDS, a strong anionic detergent that breaks apart cell membranes, will yield less DNA than the sample prepared with SDS. The null hypothesis for this experiment might be that both samples will yield an equal amount...
FAQs
Restricted Maximum Likelihood uses linear combinations of observed data constructed to eliminate fixed-effect parameters before forming the likelihood. This shifts attention toward the variation that remains after accounting for those effects, allowing residual and random-effect variance components to be estimated while recognizing that fixed effects were themselves estimated from the data. The result is especially useful when sample sizes are limited.
Standard maximum likelihood estimates variance components while treating the fitted fixed effects in a way that can introduce downward bias, particularly in smaller samples. Restricted Maximum Likelihood accounts for the uncertainty associated with estimating those effects by basing inference on combinations that remove them. Consequently, residual and random-effect variance estimates may be less biased than estimates from standard maximum likelihood.
Fixed effects represent systematic differences that the model accounts for, whereas random effects represent sources of variation whose variances are estimated. Restricted Maximum Likelihood separates these roles by removing fixed-effect contributions from the likelihood calculations and estimating the remaining variance components. This distinction helps researchers identify how much variation belongs to residual differences versus modeled random sources.
Each estimated component describes a distinct source of variation represented in the linear mixed model, including residual variation and variation associated with random effects. Comparing these components helps researchers partition biological or experimental variability rather than treating all differences as one undifferentiated quantity. That partition can support conclusions about biological differences and the relative importance of modeled sources of variation.
The method is useful when observations are organized through repeated measurements or hierarchical experiments, where variation may arise from more than one level of the design. A linear mixed model can represent these sources through fixed and random effects, while Restricted Maximum Likelihood estimates their variance components. Researchers can then distinguish residual variability from variation associated with the modeled structure.
In family or population data, and in quantitative genetic models, the method helps estimate variance components associated with structured biological variation. Those estimates provide a basis for partitioning variation and assessing heritability, while accounting for uncertainty from fixed effects. The resulting analysis can help researchers draw more reliable conclusions about differences among biological groups or experimental conditions.