readme.aireml
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readme.aireml [2014/09/05 16:12] – shogo | readme.aireml [2016/10/21 22:15] – [Options] shogo | ||
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===== Summary ===== | ===== Summary ===== | ||
- | A modification of REMLF90 for estimating variances with the Average-Information algorithm. Initially written by Shogo Tsuruta in 03/ | + | A modification of REMLF90 for estimating variances with the Average-Information algorithm. Initially written by Shogo Tsuruta in 03/99-07/99. AIREMLF90 uses a second derivative REML algorithm with extra heuristics, as is described in Jensen et al. (1996-7). For most models, it converges in far fewer rounds than EM-REML as implemented in REMLF90. While typically REMLF90 takes 50-300 rounds to converge, AIREMLF90 converges in 5-15 rounds and to a higher accuracy. The final results will be saved in " |
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- | AIREMLF90 uses a second derivative REML algrithm with extra heuristics, as is described in Jensen et al. (1996-7). For most models, it converges in far fewer rounds than EM-REML as implemented in REMLF90. While typically REMLF90 takes 50-300 rounds to converge, AIREMLF90 converges in 5-15 rounds and to a higher accuracy. For selected models, AI-REML may fail to converge when the covariance matrix is close to non-positive definite. Adjust sensitivity of the program by setting the appropriate tolerance or setting good starting values. The final results will be saved in " | ||
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See PREGSF90 with genotypes (SNP) for options. | See PREGSF90 with genotypes (SNP) for options. | ||
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OPTION maxrounds 1000 | OPTION maxrounds 1000 | ||
</ | </ | ||
- | Maximum rounds (default 5000). When the number = 0, the program calculates BLUP without iterating REML and some statistics (SE, ...). | + | Maximum rounds (default 5000). When the number = 0, the program calculates BLUP without iterating REML and some statistics (-2logL, AIC, SE for (co)variances, ...). |
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OPTION EM-REML 10 | OPTION EM-REML 10 | ||
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OPTION missing -999 | OPTION missing -999 | ||
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- | Specify the missing value (default 0). | + | Specify the missing value (default 0) in integer. |
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OPTION constant_var 5 1 2 ... | OPTION constant_var 5 1 2 ... | ||
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< | < | ||
- | As an alternative of SE, calculate SD for function of (co)variances by repeated sampling of parameters estimates from their asymptotic multivariate normal distribution, | + | As an alternative of SE, calculate SD for function of (co)variances by repeated sampling of parameters estimates from their asymptotic multivariate normal distribution, |
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''< | ''< | ||
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A formula to calculate a function of (co)variances to estimate SD. All terms of the function should be written with no spaces.\\ | A formula to calculate a function of (co)variances to estimate SD. All terms of the function should be written with no spaces.\\ | ||
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- | Each term of the function corresponds to (co)variance elements and could include any random effects (G, PE, ...) and residual (R) (co)variances.\\ | + | Each term of the function corresponds to (co)variance elements and could include any random effects (G) and residual (R) (co)variances.\\ |
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Notation is with reference to the effect number and the trait number ('' | Notation is with reference to the effect number and the trait number ('' | ||
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Set the number of samples to calculate SE for function of (co)variances.\\ | Set the number of samples to calculate SE for function of (co)variances.\\ | ||
- | default value 5000 | + | default value 10000 |
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Indicate to store in file samples of (co)variances function for postprocessing (histogram, etc.) | Indicate to store in file samples of (co)variances function for postprocessing (histogram, etc.) | ||
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+ | ===== Tricks ===== | ||
+ | When the covariance matrix is close to non-positive definite, the AIREMLF90 may not converge. | ||
+ | There are two options you might want to try: | ||
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+ | 1. change the tolerance value (xx) in the option: | ||
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+ | OPTION tol xx | ||
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+ | to a very strict value (e.g., 1d-20) or a lenient value (1d-06). | ||
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+ | 2. use an option to use EM-REML inside AI-REML: | ||
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+ | OPTION EM-REML xx | ||
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+ | where xx is the number of iterations for EM-REML you expect to get a good starting value for AI-REML. After running xx rounds with EM-REML, the AIREMLF90 program will automatically switch from EM-REML to AI-REML using the last estimate from EM-REML as a starting value for AI-REML. | ||
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readme.aireml.txt · Last modified: 2024/03/25 18:22 by 127.0.0.1