A statistical model is a formalization of relationships between variables in the form of mathematical equations. A statistical model describes how one or more random variables are related to one or more random variables. The model is statistical as the variables are not deterministically but ...

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15 views

R: Is it possible to estimate the poisson noise?

I have a dataset of many discrete counts (RNAseq read counts per base), which contain both real signals and background noise. The noise is random, and should be poisson distributed. What I would ...
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16 views

ARMA(p,q) model interpreting PACF and ACF

Here I have two time series (ACF, PACF), one on the left and one on the right. I have difficulties interpreting the results. Both PACF/ACF couples look the same and I can't distinguish any geometric ...
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24 views

Logistic vs. Linear regression for recovery rate modeling

i am trying to model recovery rates in my data that are in the range of (-.1,+1). Around 8% of my observations are negative too. Broadly, below is the dist.: RR<0: 8% RR=0: 30% RR>0 and ...
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1answer
41 views

Post hoc selection of important features in random forest?

I want to guarantee a parsimonious random forest (few features used). What are methods to do this? It was suggested to me to get the feature importance after the model was created, and then create a ...
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6 views

Looking for catalog of “mechanism classes” that give rise to specific curve shapes

(I apologize for the length of this post. I don't know how to frame the question more succinctly.) I have some experimental data, in the form of a collection of curves with fairly little noise, ...
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1answer
42 views

Autoregressive distributed lag models ADL(p,q) determining amount of lags

I would like to know how I can determine the appropriate amount of lags in Matlab or another statistical package. I'm getting confused with VAR models and ARMAX models all the time and I'm a little ...
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12 views

What's the best way to perform driver analysis when you have less observations? [closed]

I have a data which has very less observations when compared to the variables (for 50 variables I have 130 observations).What is the best way to identify the drivers?
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8 views

Different sufficiency condition for Goods and bads

I am building an underwriting model for a bank with the following construct Development Sample Window - Accounts opened before Jun'13 (i.e. have completed atleast 12 months as of Jun'14) Bad ...
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1answer
27 views

Predictive Model from Counts Data

I have some data that is the number of times a person visited a doctors office over a course of $5$ years. I want to create a model that would be able to predict the most likely number of counts that ...
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11 views

How do current image-to-3D model systems work?

I understand that at least one system for automatically modeling 3D objects from image data exists. Autodesk appears to have developed a good method. Does anyone know the basic structure and ...
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1answer
18 views

Bidding Collusion Question: Probability of Identical Bids

I was asked this question. My initial conclusion is that there isn't enough information to calculate the probability. I would appreciate it if anyone could provide provide their insight. Scenario: ...
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1answer
29 views

Control variables- Difference in Difference

I am carrying out a difference in difference estimation. Regarding control variables addition I am kinda confused. Am I to add control variables which affect the dependent variable or control ...
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17 views

Interpreting the Johansen cointegration test output

I am running the Johansen cointegration test using 2 non-stationary time-series, as suggested by the literature. The output I got is the following: ...
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1answer
42 views

Linear Model or Logistic Model: Can Someone Recommend a Book?

I have a huge data set that looks roughly like this: ...
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2answers
44 views

Is cross validation for validating a model or for selecting best model in different kinds of models?

I am confused about the concept of cross validation and its usage. As I read about cross validation before, it is a way of validating a model. I did cross validation in my project (developing ...
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1answer
47 views

What resolution should I be using for residuals vs fitted values plot from a linear regression?

I made this linear regression that shows how well estimated animal locations (longitude) predict actual animal locations. ...
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12 views

Artificial distribution to best match an actual one

There's a problem I am struggling to solve, if anything because I can't find the right angle from which to attack it. It's basically a fitting problem, and possibly a topological one, although I'm not ...
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1answer
37 views

What statistical method to correct systematic error in the output of a economic optimization model?

I am working with an economic optimization model which attempts to model the dynamics of a certain commodity market (prices, quantities, production etc.) for different frequencies (monthly, quarterly, ...
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56 views

Arima function doesn't consider seasonal components

Currently trying to fit several models to some data sets in order to find an accurate enough one, I ran into some difficulties with the Arima function of the ...
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1answer
36 views

Is positive coefficient of price correct in a multiple regression model

I am currently undertaking forecasting of energy sales (kWh) for our industrial customers. From historical data gathered from 1993 to 2013, a graph of price per kwh against sales kwh shows a positive ...
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1answer
32 views

Geodesic distance and mean

My data-set consists of points in globe. Suppose a User visits locations $l_1,l_2,\dots l_n$ (each location in $(lat, long)$ in the city with probability $p_1,p_2,\dots,p_n$ and I want to calculate ...
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1answer
24 views

Model specification with Deflators: methodological question on forecast model

I am trying to build a model to predict one year ahead Earnings per share $(t+1)$ based on variables in year $t$. I’ve seen a lot of models in practice that use the following methodology: ...
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17 views

VARMAX model in R

Is there a function in R that estimates the VARMAX model? There is one for a VARX (MTS package), but I didn't find one that works with the MA part also...
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1answer
29 views

Simulate data by using existing dataset

I have a complete dataset with input variables and response variables. I would like to perform a simulation where I give the input variables and generate randomly the response variables. Is there a ...
4
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1answer
90 views

Model with non-linear transformation

I don't understand this concept well and need help. I was choosing whether to use a linear model or apply a non-linear transformation in my model formula. To do a diagnostic, I quickly plotted my ...
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1answer
32 views

Specifying lag in `dlnm` when passing arguments to `crossbasis`

I am using the dlnm package to build a finite distribute lag linear model. I intend on testing the model-fit based on various lag levels to assess which lag is ...
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1answer
47 views

How can I (Should I?) use logistic regression/the logit function to predict outcome of a tennis match in a simple simulator?

I am trying to create a tennis simulator. Specifically I am trying to make a 'random' simulator so that I can see how many times streaks of wins or losses occur, and then compare this to historical ...
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1answer
41 views

Regression on wavy angular data?

I'm a newbie at stats/machine learning so please bare with me. This plot is a result of an experiment that attempts to find the perceived angle of a stimulus. The stimulus is placed at a position ...
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1answer
62 views

How to capture & present lm model output from R

After running iterations of lm() in R, I am now stuck with which components of the model's output to present and how to present them. I know that the $R^{2}$ value, ...
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2answers
45 views

What does initial level of GDP mean?

This might come as a very trivial thing and way below standards of this group but I am struggling to figure out what do the authors mean when they say that they have used initial level of income in ...
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1answer
13 views

Alternative to MAPE when the data is not a time series

I have a data set where many of the actual values are zero, so I can't use MAPE. It's not a time series, so I can't use MASE ala our very own Rob Hyndman. Is there another alternative to MAPE that I ...
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0answers
25 views

Overly-sensitive goodness of fit measure: where did I go wrong?

I'm using the chi-squared goodness-of-fit measure to evaluate instances of a fairly complicated model, but the evaluation is unbelievably sensitive to small variations in the model parameter values. ...
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9 views

How to model my data into a probit

I am beginning my thesis, and I need some advice. I am trying to estimate a probit model. The binary dependent variable is employment status, and the independent variables include network size, age, ...
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0answers
28 views

Estimating a distribution from a dataset with multiple parameters

How would you go about solving the following problem? You're an insurance company who writes workers compensation policies. You want to build a probability distribution for the number of annual ...
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1answer
9 views

procedure of statistical modeling of sample

I never did the statistical modeling of sample. Usually i was engaged in common statistical procedures(descriptive statistic, correlation, regression, factor analysis and so on). Now i decided find ...
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0answers
28 views

Naïve Random Walk Model as a Benchmark for Predictive Model

I constructed a predictive model for $Y_{i,t+\tau}$ for $\tau=1 to 3$ using panel data with firm and year observations: $Y_{i,t+\tau}=a+bX_{i,t}+e_{i,t+\tau}$ and i'm trying to measure the ...
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0answers
47 views

Estimation parameters for latent (unobserved) variable

Here is my problem: I have 3 variables $X,Y,Z$ : $X$ is the number of clicks we observed on an web advertisement; $Y$ is the number of time a customer do a sign-up on the website after clicking ...
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0answers
19 views

How to model the number of pedestrian crossed for a certain distance, and the number of smokers in particular?

In a city of 2 millions people, with 950km of streets, I'd like to estimate the probability to get close to a smoker i.e. less than 10 meter. For that let's represent streets without width, in a ...
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1answer
95 views

modelling data that contains only ones and zeros

I'm new to modelling this type of data, and I got punished for asking this on stackoverflow... I have a dataset where the predictive variables contain only ones and zeros, and the response variable ...
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0answers
25 views

Different models for different quantile functions possible?

My aim is to estimate the 2.5%- and 97.5%-quantile function (to get reference intervals) for a specific score in dependence of age separated by classes of a third variable cag. So first I built 11 ...
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2answers
56 views

Steps in making a Global Regression Model

I saw a journal article [1] saying that he constructed the following S-curve model : $$y=\exp\left({\beta_1 + \frac{\beta_2}{x}}\right) + \mathrm{residual}$$ The topic was about a global regression ...
3
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2answers
62 views

What are some methods for generating simulated time series data for use in modeling?

I have a data set which consists of 50 observed years for which I have date and inflow values between a river and a reservoir. The data is formatted as follows: ...
3
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1answer
36 views

Fit nonlinear parameter

I'm attempting to fit this model: $P = C_0 + C_1*U^r$ Given known vectors of observations $P$ and $U$, I want to fit values for $C_0$, $C_1$ and $r$. How do I make this fit in R? or preferably GSL ...
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1answer
36 views

When making a predictive model that is predicting a continuous outcome, how does one arrive at the final prediction?

For instance, a prediction of 1 million could be: A weighted average of various predictions. ex. a .5 chance of 2 million, a .5 chance of 0, for an expected value of 1 million; or The prediction ...
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1answer
89 views

What econometric model to forecast a seasonal commodity demand while incorporating exogenous Information?

I have a monthly commodity demand and try to forecast this series for the next 5 years. Here is a plot: Of course, the natural approach to forecast this seasonality would be some kind exponential ...
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0answers
12 views

Should I use coefficient correlation or multiple linear regression to build this scoring model?

Hi I am a junior Data analyst at a non-profit and I need some help with building a 'donor scoring model' to help us identify potential 'good' donors. I am attempting to build a donor scoring model by ...
3
votes
1answer
27 views

Non-constant standard deviation in residuals

I am fitting a model in the frequency domain, and my fit looks as follows: As you can see, the model function does not fit the data perfectly, especially in the higher frequencies. So, I examined ...
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0answers
37 views

Logistic regression model fit assessment

I have run logistic regression on data. The concordant percentage is coming out 45. That is too low. However, Hosmer–Lemeshow test is coming out insignificant. It means we cannot reject the null ...
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2answers
114 views

Logistic Regression Model Validation

I am validating a logistic regression model. This is the first time i am validating a model. I am using split sampling method. I have split data randomly into two parts - 70% development and 30% ...
2
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1answer
56 views

Interaction effects in big data sets

I'm looking for a method to identify a shortlist of potentially good 2-way interaction terms rather than trying all possible interactions. This question is similarly asked before here but in a more ...