Cross Validated Weekly Newsletter - Monday, March 30, 2015

2015 Community Moderator Election The community moderator election is currently in the election phase. Please cast your vote by March 31! Top new questions this week: Smoothing - when to use it and when not to? There is quite an old post on William Briggs' blog which looks at the pitfalls of smoothing data and carrying that smoothed data through to analysis. The key argument is namely: If, in a moment of ... time-series smoothing   asked by NickB2014 10 votes answered by Stephan Kolassa 6 votes Why does adding a lag effect increase mean deviance in a Bayesian hierarchical model? Background: I'm currently doing some work comparing various Bayesian hierarchical models. The data $y_{ij}$ are numeric measures of well-being for participant $i$ and time $j$. I have around 1000 ... bayesian autocorrelation hierarchical-bayesian deviance   asked by Jeromy Anglim 10 votes answered by Summit 1 vote Introduction to machine learning for mathematicians In some sense this is a crosspost of mine from math.stackexchange, and I have the feeling that this site might provide a broad audience. I am looking for a mathematical introduction to machine ... machine-learning references   asked by Quickbeam2k1 10 votes answered by seanv507 7 votes Mixed-effect model design with a sampling variable I am trying to specify a formula for a linear mixed effect model (with lme4) for my experimental design, but I'm not sure I'm doing it right. The design: basically I'm measuring a response parameter ... r experiment-design mixed-effect   asked by agenis 8 votes answered by Ben Bolker 8 votes Citation for Statistical test for difference between two odds ratios? In a comment here, @gung wrote, I believe they can overlap a little (maybe ~25%) & still be significant at the 5% level. Remember that the 95% CI you see is for the individual OR, but the ... logistic confidence-interval odds-ratio references   asked by cpjh10 8 votes answered by gung 2 votes Does Stein's Paradox still hold when using the $l_1$ norm instead of the $l_2$ norm? Stein's Paradox shows that when three or more parameters are estimated simultaneously, there exist combined estimators more accurate on average (that is, having lower expected mean squared error) than ... paradox steins-phenomenon   asked by Craig Feinstein 8 votes Lasso for explanatory models: shrinked parameters or not? I'm conducting an analysis where the primary goal is to understand the data. The dataset is large enough for cross-validation (10k), and predictors include both continuous and dummy variables, and the ... lasso explanatory   asked by mbokulic 7 votes answered by TrynnaDoStat 4 votes Greatest hits from previous weeks: How would you explain covariance to someone who understands only the mean? ...assuming that I'm able to augment their knowledge about variance in an intuitive fashion ( Understanding "variance" intuitively ) or by saying: It's the average distance of the data ... variance covariance intuition   asked by PhD 56 votes answered by whuber 101 votes Explaining to laypeople why bootstrapping works I recently used bootstrapping to estimate confidence intervals for a project. Someone who doesn't know much about statistics recently asked me to explain why bootstrapping works, i.e., why is it that ... bootstrap communication   asked by Alan H. 116 votes answered by conjugateprior 73 votes Can you answer these? Can complete separation between a continuous predictor and a random effect cause failure to converge in a logit GLMM? I'm running a logit mixed-effects model on binary data with a 2x2 within-subjects design, with subjects and items as crossed random effects, and the two independent variables deviation-contrast coded. ... r logistic convergence glmm glmer   asked by exfalso 2 votes Copula compatibility problem Suppose I have a 3-Copula which I would like to construct with two 2-Copula's, as the following construct: $$ C_2(u, C_1(v,w)) = C(u,v,w) $$ My question is, if $C$ is known to be a valid copula ... copula   asked by Kiran K. 2 votes A YouTube View Estimator Here's a thought experiment that I can't come up with a good answer for. Imagine you have 5 YouTube videos that you want to reach 50,000 views (10,000 views per video) by the 10th day after ... basic-concepts   asked by MetroidPrime77 2 votes

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