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The '''deviance information criterion''' ('''DIC''') is a hierarchical modeling generalization of the AIC ([[Akaike information criterion]]) and BIC ([[Schwarz criterion|Bayesian information criterion]], also known as the Schwarz criterion). It is particularly useful in [[Bayesian inference|Bayesian]] [[model selection]] problems where the [[posterior distribution]]s of the [[statistical model|model]]s have been obtained by [[Markov chain Monte Carlo]] (MCMC) simulation. Like AIC and BIC it is an asymptotic approximation as the sample size becomes large. It is only valid when the posterior distribution is approximately [[multivariate normal distribution|multivariate normal]]. | |||
Define the [[deviance (statistics)|deviance]] as <math> D(\theta)=-2 \log(p(y|\theta))+C\, </math>, where <math>y\,</math> are the data, <math>\theta\,</math> are the unknown parameters of the model and <math> p(y|\theta)\, </math> is the [[likelihood function]]. <math>C\,</math> is a constant that cancels out in all calculations that compare different models, and which therefore does not need to be known. | |||
The [[expected value|expectation]] <math>\bar{D}=\mathbf{E}^\theta[D(\theta)]</math> is a measure of how well the model fits the data; the larger this is, the worse the fit. | |||
The effective number of parameters of the model is computed as <math>p_D=\bar{D}-D(\bar{\theta})</math>, where <math>\bar{\theta}</math> is the expectation of <math>\theta\,</math>. The larger this is, the ''easier'' it is for the model to fit the data. | |||
The deviance information criterion is calculated as | |||
:<math>\mathit{DIC} = p_D+\bar{D},</math> | |||
or equivalently as | |||
:<math>\mathit{DIC} = D(\bar{\theta})+2 p_D.</math> | |||
From this later form, the connection with Akaike's information criterion is evident. | |||
The idea is that models with smaller DIC should be preferred to models with larger DIC. Models are penalized both by the value of <math>\bar{D}</math>, which favors a good fit, but also (in common with AIC and BIC) by the effective number of parameters <math>p_D\,</math>. Since <math> \bar D </math> will decrease as the number of parameters in a model increases, the <math>p_D\,</math> term compensates for this effect by favoring models with a smaller number of parameters. | |||
The advantage of DIC over other criteria in the case of Bayesian model selection is that the DIC is easily calculated from the samples generated by a Markov chain Monte Carlo simulation. AIC and BIC require calculating the likelihood at its maximum over <math>\theta\,</math>, which is not readily available from the MCMC simulation. But to calculate DIC, simply compute <math>\bar{D}</math> as the average of <math>D(\theta)\,</math> over the samples of <math>\theta\,</math>, and <math>D(\bar{\theta})</math> as the value of <math>D\,</math> evaluated at the average of the samples of <math> \theta\, </math>. Then the DIC follows directly from these approximations. Claeskens and Hjort (2008, Ch. 3.5) show that the DIC is [[asymptotic distribution|large-sample]] equivalent to the natural model-robust version of the AIC. | |||
In the derivation of DIC, it is assumed that the specified parametric family of probability distributions that generate future observations encompasses the true model. This assumption does not always hold, and it is desirable to consider model assessment procedures in that scenario. | |||
Also, the observed data are used both to construct the posterior distribution and to evaluate the estimated models. | |||
Therefore, DIC tends to select over-fitted models. | |||
Recently, these issues are resolved by Ando (2007), Bayesian predictive information criterion, BPIC. | |||
To avoid the over-fitting problems of DIC, Ando (2011) developed Bayesian model selection criteria from a predictive view point. | |||
The criterion is calculated as | |||
:<math>\mathit{IC} = -2\mathbf{E}^\theta[ \log(p(y|\theta))]+2p_D.</math> | |||
The first term is a measure of how well the model fits the data, while the second term is a penalty on the model complexity. | |||
==See also== | |||
* [[Akaike information criterion]] (AIC) | |||
* [[Bayesian information criterion]] (BIC) | |||
* [[Bayesian predictive information criterion]] (BPIC) | |||
* [[Focused information criterion]] (FIC) | |||
* [[Kullback–Leibler divergence]] | |||
* [[Jensen–Shannon divergence]] | |||
==References== | |||
{{refbegin}} | |||
*{{cite journal | |||
| first = Tomohiro | last = Ando | |||
| year = 2007 | |||
| title = Bayesian predictive information criterion for the evaluation of hierarchical Bayesian and empirical Bayes models | |||
| journal = [[Biometrika]] | |||
| volume = 94 | pages = 443–458 | |||
| doi = 10.1093/biomet/asm017 | |||
| issue = 2 | |||
}} | |||
*{{cite journal | |||
| first = Tomohiro | last = Ando | |||
| year = 2011 | |||
| title = Predictive Bayesian model selection | |||
| journal = [[American Journal of Mathematical and Management Sciences]] | |||
| volume = 31 | pages = 13–38 | |||
}} | |||
* Claeskens, G, and [[Nils Lid Hjort|Hjort, N.L.]] (2008). ''Model Selection and Model Averaging'', Cambridge. Section 3.5. | |||
*{{cite book | |||
| first = Andrew | last = Gelman | |||
| first2 = John B. |last2=Carlin | |||
| first3=Hal. S. |last3=Stern | |||
| first4= Donald B. |last4=Rubin |authorlink4=Donald Rubin | |||
| year = 2004 | |||
| title = Bayesian Data Analysis | |||
| edition = 2nd | |||
| pages = 182–184 | |||
| publisher = Chapman & Hall/CRC | |||
| location = Boca Raton, Florida | |||
| isbn = 1-58488-388-X | |||
| id = {{LCC|QA279.5.B386|2004}} | mr = 2027492 | |||
}} | |||
* van der Linde, A. (2005). "DIC in variable selection", ''Statistica Neerlandica'', 59: 45-56. doi:[http://dx.doi.org/10.1111/j.1467-9574.2005.00278.x 10.1111/j.1467-9574.2005.00278.x] | |||
*{{cite journal | |||
| first = David J. | last = Spiegelhalter | authorlink = David Spiegelhalter | |||
| first2 = Nicola G. |last2=Best | |||
| first3=Bradley P. |last3=Carlin | |||
|first4= Angelika |last4=van der Linde | |||
|date=October 2002 | |||
| title = Bayesian measures of model complexity and fit (with discussion) | |||
| journal = [[Journal of the Royal Statistical Society, Series B]] | |||
| volume = 64 | issue = 4 | pages = 583–639 | |||
| doi = 10.1111/1467-9868.00353 |mr=1979380 | jstor = 3088806 | |||
}} | |||
{{refend}} | |||
[[Category:Bayesian statistics]] | |||
[[Category:Regression variable selection]] |
Revision as of 11:17, 26 April 2013
The deviance information criterion (DIC) is a hierarchical modeling generalization of the AIC (Akaike information criterion) and BIC (Bayesian information criterion, also known as the Schwarz criterion). It is particularly useful in Bayesian model selection problems where the posterior distributions of the models have been obtained by Markov chain Monte Carlo (MCMC) simulation. Like AIC and BIC it is an asymptotic approximation as the sample size becomes large. It is only valid when the posterior distribution is approximately multivariate normal.
Define the deviance as , where are the data, are the unknown parameters of the model and is the likelihood function. is a constant that cancels out in all calculations that compare different models, and which therefore does not need to be known.
The expectation is a measure of how well the model fits the data; the larger this is, the worse the fit.
The effective number of parameters of the model is computed as , where is the expectation of . The larger this is, the easier it is for the model to fit the data.
The deviance information criterion is calculated as
or equivalently as
From this later form, the connection with Akaike's information criterion is evident.
The idea is that models with smaller DIC should be preferred to models with larger DIC. Models are penalized both by the value of , which favors a good fit, but also (in common with AIC and BIC) by the effective number of parameters . Since will decrease as the number of parameters in a model increases, the term compensates for this effect by favoring models with a smaller number of parameters.
The advantage of DIC over other criteria in the case of Bayesian model selection is that the DIC is easily calculated from the samples generated by a Markov chain Monte Carlo simulation. AIC and BIC require calculating the likelihood at its maximum over , which is not readily available from the MCMC simulation. But to calculate DIC, simply compute as the average of over the samples of , and as the value of evaluated at the average of the samples of . Then the DIC follows directly from these approximations. Claeskens and Hjort (2008, Ch. 3.5) show that the DIC is large-sample equivalent to the natural model-robust version of the AIC.
In the derivation of DIC, it is assumed that the specified parametric family of probability distributions that generate future observations encompasses the true model. This assumption does not always hold, and it is desirable to consider model assessment procedures in that scenario. Also, the observed data are used both to construct the posterior distribution and to evaluate the estimated models. Therefore, DIC tends to select over-fitted models. Recently, these issues are resolved by Ando (2007), Bayesian predictive information criterion, BPIC.
To avoid the over-fitting problems of DIC, Ando (2011) developed Bayesian model selection criteria from a predictive view point. The criterion is calculated as
The first term is a measure of how well the model fits the data, while the second term is a penalty on the model complexity.
See also
- Akaike information criterion (AIC)
- Bayesian information criterion (BIC)
- Bayesian predictive information criterion (BPIC)
- Focused information criterion (FIC)
- Kullback–Leibler divergence
- Jensen–Shannon divergence
References
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The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - Claeskens, G, and Hjort, N.L. (2008). Model Selection and Model Averaging, Cambridge. Section 3.5.
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- One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang