A statistical model is a formalization of relationships between variables in the form of mathematical equations. The model is statistical as the variables are not deterministically but stochastically related.

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Possible to generate partworth utilities in LIMDEP/Nlogit?

Is it possible to generate partworth utilities for certain variables in a discrete model in LIMDEP/NLOGIT? I'm aware of the ;Utility =u1 command, which generates ...
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23 views

How to calculate the probability of success of a Logistic Regression model with a single continuous predictor?

I have a logistic regression model below, predicting a dichotomous variable type from a single continuous predictor fatigue. Using the coefficients below I can obtain the increase in the odds of a ...
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1answer
83 views

Model selection, issues of judgement

I have a general question on model selection strategies in regression models. In my research, the main goal is rarely prediction but almost always estimation of effects of certain variables. I have ...
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16 views

How to analyse the influence of 100 categorical or continuous predictors on one continuous response?

I am analysing a genetic dataset that consists of 288 individuals, 100 genetic markers as predictors and one continuos variable (day of death) as outcome. Each predictor has three categories or ...
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32 views

Pros&Cons of Hidden Markov Models in Time Series Forecasting

What are the advantages and disadvantages of Hidden Markov Models in forecasting values of a time series (compared to other methods, e.g. ARIMA)?
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13 views

What is the set of all variables?

For instance, when we have a conditional relationship in a model (e.g. entry in the Gaussian inverse covariance) and want to claim that this parameter is the true population parameter, we have to ...
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2answers
43 views

Response Surface Methodology (RSM) for A Mathematical Model

I would like to create a second order polynomial model using Response Surface Methodology (RSM) for a non-polynomial mathematical model. For example, I would like to represent $f(x)=x_1 + \sin(x_1x_2) ...
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20 views

The best model to analyse this data set: Comparing bacteria communities within calves

The design is like this: I have 18 calves in the experiment, and all these calves were divided into 3 groups with 6 calves in each group. The 6 calves in group 1 were euthanized at the end of the ...
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1answer
17 views

Can the Breusch-Pagan test be applied to GLM?

I have developed a model to test if a relationship is unimodal by using a Gaussian GLM. In an effort to diagnose the various assumptions of linear models I used the Breusch-Pagan test to determine ...
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11 views

Reporting Results from a Mixed ANOVA

I have done a Mixed ANOVA on some data from a tennis serving experiment and am slightly confused on how to report the results. I am comparing the effect of self-talk (either instructional or ...
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48 views

How to express a Poisson regression equation as a quasi-Poisson

I was reading this paper: http://www.researchgate.net/publication/13878515_A_simple_non-linear_model_in_incidence_prediction and was wondering whether the equations 1 and 3 presented in the paper to ...
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10 views

Correct or most valuable way to model consumption/usage among users of a product or system?

Is there a best method for approximating average daily consumption among users of a product? I'll use an example to illustrate. We have monthly data for the past year (we have all data since launch) ...
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1answer
20 views

Consumer Predicted Probability Function

I have the following data for the last year for several thousand clients: Client ID Last Interaction Date with Business Last Buy Date No of items bought Total value spend in $ I want to create a ...
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13 views

# of free parameters in AIC for grid search like threshold model

I need to compare fit of two models. They are dose-response function with Poisson regression framework. Model 1 y=bx Model 2 y=0 if x is less than x0 bx otherwise (x0=0,1,2,...) For model ...
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22 views

Multiple tests, summary of clogit

I have 10 exposure variables that i would like to analyze univariate. I've applied the conditional logistic regression model for each exposure and then used the summary function for each one of them. ...
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18 views

Which validation method to choose if the number of instances is limited?

I have a question regarding how to measure the performance of a model when the distribution of instances per class is limited. In my scenario I have five data sets $\mathcal{D}_{1}, \mathcal{D}_{2}, ...
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18 views

Multivariate binary time series

I have several concurrent time-series, which have binary response: Yi = (yi1, ... , yiT) where yit = 1 or 0 at an observed time t. i = 1, ...,n (where n is the total number of concurrent time ...
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6answers
3k views

Should parsimony really still be the gold standard?

Just a thought: Parsimonious models have always been the default go-to in model selection, but to what degree is this approach outdated? I'm curious about how much our tendency toward parsimony is a ...
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1answer
39 views

How to approximate Bayes Factor?

I am searching for a computationally simple way to approximate a Bayes Factor. Currently, I'm using an approach which seems pretty logical to me but I would still be interested to know if this is ...
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2answers
187 views

Statistical Model: How much will my open bar at my wedding cost?

I am getting married in November in Mexico and after fidgeting with my wedding budget, I was wondering if anyone had any insight into how I should approach my problem. Thought it was relatively ...
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2answers
42 views

Computing fit of model to horizontally-misalligned time-series data

I have a model that predicts the level of harmonic tension in a piece of music, at every note/chord in the piece. I also have participant data (time series) that contains subjective ratings of tension ...
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1answer
25 views

How can I work out effect of advertising spend on website traffic using a model?

I don't really know much about stats so if the following sounds completely absurd, i'm sorry. I've got 18 months of retail data Jan 2014 to now. It's an entirely online business, and I've got daily, ...
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14 views

Predicting responses to test-data variables that lay far outside model training-data variable range

What can one do to improve model predicting accuracy when using test data that has a variable with magnitudes far outside the range of that variable in the training data? Example: This question ...
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1answer
17 views

Methodological test for choosing 'worse' models that make 'better' (more realistic) predictions?

I've run 4 models (simple LM, quadratic model, GLMM, and GLMM with quadratic) to predict tree age (age) from tree diameter (D) for each of 42 species (SPEC). The diameter data has all been log ...
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9 views

The relationship between the intercept in logit and model power?

Say I have 12 regressions, each is forecasting a future event further out in the future. Regression 1 is 1 period forward and regression 12 is twelve periods forward. I've noticed that the power of my ...
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6 views

Which regression model to use for order-sensitive sequences of symbols / apps?

I have a list of sequences of symbols, representing apps used by a smartphone user within a certain time frame. For example (Whatsapp, Facebook, Calender) might be one such sequence. To each list ...
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1answer
31 views

A comprehension question to conditional heteroscedasticity/GARCH

I have a time series with strong seasonality. At specific time periods/seasons there is also a stronger Variance than in other time periods/seasons. Is that an example of conditional ...
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10 views

Why are standard errors the same in lag-distributed model in R?

I am running a lag-distributed model ordinary least squares in which a set of units are all treated in the same year. I am including a 2 lags and 2 leads to see if there were any "anticipation" or ...
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21 views

How to write an equation for a spline regression

I have this basic regression model that I would like to make into a spline with a knot at -1. How would I write it? Is it possible for me to write it as a single equation where I subtract 1? Here's ...
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25 views

Why are my random effects averaging out to zero in my Monte Carlo Simulation?

I'm using SAS to conduct a Monte Carlo simulation for a linear mixed model of the form y = Bx + Zu + e, where B and Z are design matrices for the fixed and random effects, x and u, respectively and e ...
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1answer
38 views

Interpreting interactions when main effect is not significant

I just started fooling around with R and I am quite struggling with mixed models: I have the following experimental layout: Seven different viruses, including ctrl virus; 27 mice, randomly infected ...
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21 views

How to interpret modification indices output of structural equation models?

I am trying following example of structural equation model in R: ...
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1answer
145 views

How to interpret this lavaan structural equation model?

I created following structural equation model from iris data set using lavaan package in R: How do I interpret these numbers. The output (of sem() function of lavaan package) is given below. It ...
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11 views

Analysis of PValues Matrix

in clinical environment I'm setting up a model to identify fraudolent behaviours from specific sites, calculating for each site some aspects that could lead to a p-value (this approach is based on a ...
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1answer
64 views

R: interaction in model output

Let's say you're trying to fit a model to a dataset that includes categorical variables, group (A or B) and treatment (1, 2, 3 or 4). In R, your model formula would be DV ~ group * treatment (DV ...
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2answers
113 views

Logistic regression results (coefficients) counterintuitive?

I ran a logistic regression model on SPSS with a dependent variable of yes/no whether you chose bus or not (the other being personal vehicle) and 5 independent variables (Waiting Time, Trip Time, ...
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14 views

Interpreting interaction results between 2 categorical variables in GLM (SPSS)

I have a very simple question. I just want to know how to interpret the results of an interaction between 2 categorical variables (each has 2 levels--the first variable, SES, has upper and lower SES; ...
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1answer
39 views

Combining Forecasts

I am in the process of creating one well-rounded forecast, and in my research I found a few mentionings approving the use of several forecasts combined into one. I really like this idea but I have ...
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11 views

reduced multilabel-dataset performance evaluation

Assume a multilabel problem with given ground truth, where each training instance can have one or more of 3 labels A,B and C, e.g: ...
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34 views

How to compare 3 slopes in a repeated measures Linear Mixed Model

I am running a linear mixed model with a random intercept. I have 3 groups (0, 1, 2) with a repeated measure (time) of a test score. I am comparing trajectories and since SPSS uses the last group as ...
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13 views

Corroborating/Conflicting partial correlation and covariance matrix from mixed model

I have a project looking at reaction times of coordinated movements; there is a visual signal and the participant must look and point at a target. We measured the reaction time (ms) of the motor ...
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29 views

Use a model to reduce sample size?

I have a consultant that is proposing that he can reduce my sample size by using a model that is built off of previous samples. My first response was "NEVER EVER EVER EVER DO THIS". However, after ...
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45 views

Practical beginners resource for building a dynamic OLS model

I need to model the current account balance of a country. The regressors are the real effective exchange rate, the domestic GDP and the GDP of the world. I am using data for 30 years (in logs). It is ...
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16 views

Alternative to weighted kappa?

I want to compare modeled species occurrence with observed occurrence data. Using confusion matrix and weighed kappa seems to be a good option. In contrast to the normal kappa the weighted kappa takes ...
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46 views

4-point Likert scale

I have compiled a questionnaire using a glossary of terms. I have 4 options that people can select. The terms are; I don't understand the word and I can't define it / I understand it but I never use ...
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1answer
193 views

How to fit piecewise constant (or step-function) model and compare to logistic model in R

I have x, y data where x is position (along a transect) and y is a continuous variable (e.g. temperature). ...
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18 views

Model with two ordinal variables

I have question about the ordinal variables in model and using them correctly. Let's say I have a model that explains income by education and age. Age is continous and education is ordinal ex. can be ...
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18 views

Estimate VAR model from data about lags

Does anybody have any idea how i would write the var model based on this table? What coefficients should be included? Any hint will be much appreciated. Thank you!
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1answer
60 views

What is the model similar to 2SLS, but not for IV?

I am analyzing the effect of foreign aid on democracy and I would like to test following hypothesis (I simplified the original version): The amount of aid the country received and the corruption ...
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1answer
29 views

Best method for predicting a numeric response from multiple proportional predictors?

I have some data where I want to predict a continuous, approximately normally distributed response/dependent variable with three predictors which are all proportions (i.e. 0-1). The three proportions ...