# All Questions

4 views

### Selecting genes more affected in treatment A than treatment B

We are trying to test the hypothesis that a mild mutation of a gene has few effects on the expression of the transcriptome than complete deletion. Further we wish to test the hypothesis that the genes ...
4 views

### comparing gam model with different length data

Consider the following example: ...
8 views

### Using LDA in non-realtime twitter data

I try to understand user characterization from twitter data. How can I understand the user's interest from statuses? From my researches, LDA(Latent Dirichlet Allocation)suitable for topic extraction. ...
6 views

### Marginal effect of squared variable in Probit Model

I want to estimate the following probit model $employed_t=\beta_1 age + \beta_2 age^2$ and I use the STATA code probit employed c.age##c.age Using the command margins I obtain the marginal effect ...
19 views

### Modeling data with logistic regression

I am new in statistical modeling and l am trying to model a financial data with logistic regression and I am facing a challenge here. Some of the predictor variables have integer values( negative, ...
7 views

### Assessing quality of a fixed sample size with limited information about full set

Given the level of this site these are probably intolerably newbie questions, but here goes... So I'm studying the cost of public transport in a given city. I have access to data from a hopefully ...
10 views

### Recoding a variable with three levels into a dummy variable

I need to recode the variable school setting (urban, sub-urban and rural settings) into a dummy variable. I know that when creating a dummy variable, there is one category less (so 2 rather than three ...
18 views

### Missing data: what's the best approach?

In a representative sample of country population I have very few missing data, around 3%. But when I checked the missing data per communities, I found that one of them has almost 30% of data lost. ...
8 views

### Reference Request: Human speech extraction using Machine Learning

I am trying to extract human voice from a noisy clip and studied some test upon it like, voice clipping using deep learning or MLP ann etc., then speech identification using a sequence based ...
31 views

### Elements of Statistical Learning - Tutors

I am studying the Elements of Statistical Learning (ESL) at nights and weekends to improve my understanding of the mathematics and fundamentals behind statistical learning. However, from time to time ...
10 views

### Subjects:condition interaction random effect in a growth model

I'm investigating the effect of 'Condition' (3 levels: Quiet, Intelligible, Unintelligible) on pupil response over time (intercept, linear, cubic, quadratic, quartic and quintic terms). When I use ...
11 views

### What can be inferred when multivariable ordinary least squares and quantile (median) regression yield differing results?

There lies information in a discrepancy of the (unconditional) mean and median. For example, if the median is larger than the mean, the distribution must be left-skewed. Does this kind of inference ...
9 views

### Segmenting an interval sensibly

Is there a canonical/recommended approach to or algorithm for splitting up an interval with the intent of minimizing the number of segments while keeping a high accuracy? It is essentially an ...
7 views

### What exactly do eigenvalue and eigenvector indicate? [migrated]

What exactly do eigenvalue and eigenvector indicate? I mean what is the importance in calculating them. We all know how to calculate them but I do not know the exact importance
19 views

### How to calculate loadings and use them to regress in SPSS

I am trying to build a model with 15 independent variables. However, because the parameters have been showing collinearity, I have been advised to use the Principal Component regression method. ...
17 views

### Post hoc tests from Anova() from car-package

I have a small sample unbalanced RCBD, where I have reason to suspect unequal variances, hence I wish to fit a ANOVA with type-3 SS with heterscedasticity consistent esimators. The simplest way to do ...
14 views

### Implement neural network to perform multivariate poisson regression with implied rates

I am now looking at implementing a neural network that will take in 4 input variables, and will output 24 variables. All of the output variables are related (in more than one way) to each other so I ...
35 views

### Time series forecasting using R

I have many time series(retail data). Some with trends, some seasonal, and some with neither. With period day, week or month. I need to make forecast, for each time serie. I'm looking for the most ...
21 views

### Probabilistic Classifier?

I wanna know the name of those classifiers which are based on probability or those techniques which are based on probability? (Except Bayesian Techniques.) Thanks in advance
6 views

### isn't it possible giving weight to attributes in Clementine?

I use SPSS Clementine. I need to give a weight to one of my features to be considered much more than others as it is more important. I can't find any option to do this for training a C5 tree. the ...
13 views

### Logistic regression when a covariate is measured with known but heterogenous measurement error

Let $y$ be a binary variable and $x$ be a covariate measured with known heterogeneous measurement error: $x_{i}$ ~ $\operatorname{Normal}(x^{*}_{i},\sigma_{i}^{2})$. Now suppose the relationship ...
12 views

### Pattern Recognition in Practical Problem in R

I am using R for last 4 months with basic test analysis, regression models, ANOVA etc. Now I am looking into a particular problem. In words problem can be stated like, Lets a particular machine ...
5 views

### How to improve simulation efficiency of method of simulated moments with random coefficient?

I have a model with two layers. There are 4 variables with random coefficients in the second layer of the model, which is a multivariate Logit. I assume the four random coefficients follow ...
34 views

### Basic statistical equation

How would I go about showing that: $$\sum_{i=1}^n (X_i-\bar{X})^2=\sum_{i=1}^n X_i^2-n\bar{X}^2\,,$$ (where $\bar{X}=\frac{1}{n}\sum_{i=1}^n X_i$)? Thank you for your help!
31 views

### Logistic regression

I'm currently suffering trying to understand statistics in class. Hopefully someone can clarify and explain in layman's language some things that I don't understand, especially relative to logistic ...
15 views

### data prediction by regression or better ways

I am working on data prediction. Given data of a random variable $X$ and $Y$, find out how to predict $Y$ from $X$. I know how to do it by linear regression, $\hat{Y} = kX + b$. But, here, $X$ is ...
7 views

### lagged covariate or time series for analyzing change over time in Hgb (limited observations) in the prediction of disease status

I want to test whether changes in Hemoglobin (Hgb) levels over time can help diagnose Myelodysplastic syndrome (MDS). I have a cohort of thousands of patients. Each patient has several Hgb ...
25 views

### Minimum observations for creating dummy variables from a categorical group variable

I have an OLS regression with around 1000 observations and created a dummy variable for at least 15 different categories (catholic, muslim, hindu etc). One of the created dummy variables (spiritual) ...
11 views

### Time Series Forecasting Method to use both Predicted and Predictor variables

I am learning Predictive modeling and building a Forecasting model to predict Insurance sales in US as a part of my academic project. I want to do Time Series forecasting. I have Y(t) as my response ...
11 views

### Sample/Null Value

I was running through question section on my stat book and the following question was posed: If our sample value is close to the null/population value, we conclude that ... I don't get if that ...
20 views

### What are some differences between confirmatory analysis and exploratory analysis?

In confirmatory analysis do you basically just test hypotheses? Then in exploratory analysis you try to generate hypotheses? In general, I know that you can first do exploratory analysis to form ...
50 views

### Using all of the data

Suppose that we have data on 1000 people. Each of these people are either from California, Texas, or Hawaii. We have various lifestyle variables on each person (e.g. age, gender, etc.). We are ...
14 views

### How to test for statistically significant differences between parameters for sigmoids fit to two different data sets?

I have two sets of data collected from two groups (group 1 in red, group 2 in blue). Each data set has been fit with a sigmoid with 4 parameters: Bottom Plateau, Top Plateau, Point of Inflection, and ...
17 views

### qqPlot with Two Outliers

If I have a QQ plot with two extreme outliers (picture below) how should I interpret it? Do I drop the outliers? Can I treat it as normal?
25 views

### finding Limiting distribution $\displaystyle\frac{\sum_{i=1}^n X_i}{\sum_{i=1}^n Y_i}$

let $X_1,X_2,\ldots,X_n$ are random sample of bernoulli distribution with parameter of $\displaystyle\frac{\theta_1}{\theta_1+\theta_2}$ and $Y_1,Y_2,\ldots,Y_n$ are random sample of geometric ...
13 views

### Multi-armed bandit algorithms vs Uplift modeling

Multi-Armed Bandit: http://en.wikipedia.org/wiki/Multi-armed_bandit Uplift Modeling: http://en.wikipedia.org/wiki/Uplift_modelling How are these two approaches different? How are they similar? Is ...
27 views

### How to interpret output of poisson.test?

Chapter 11 of Introduction to Data Science is about Poisson distributions. One example sample has 58638 observations out of 100000 with a value less than or equal to 10. ...
31 views

### Forecasting irregular time series (with R)

There are several methods to make forecasts of equidistant time series (e.g. Holt-Winters, ARIMA, ...). However I am currently working on the following irregular spaced data set, which has a varying ...
24 views

### Kolmogorov-Smirnov with parameter estimates

Can someone explain in as clear a (formalish mathematical) way as possible why the KS test in original form with parameter estimates is unreliable?
251 views

### In left skewed data, what is the relationship between mean and median?

I found this question on the open MOOC from Stanford, however the answer is not present. I think the median $\leq$ mean. Is this the case?
14 views

### Need subspace partition algorithm, not necessarily a full classifier

The image above represents a hypothetical data set of interest. For some set of points in N-dimensional space (each attribute of the data set corresponds to one dimension), I want to identify ...
12 views

### Optimal weighting matrix instrumental variables estimator

The formula for the optimal weighting matrix when you perform regression with more instrumental variables than endogenous predictors is the following: $W_{opt} = (\frac{1}{N}Z'Z)^{-1}$ This tells ...
514 views

### Do I have to learn SAS if I want to go into industry?

I am currently a PhD student in Biostatistics (finishing my 2nd year). My original goal when entering graduate school was to go into academia. Recently I have been debating this choice and wondering ...
89 views

### Variance of Z for Z = X + Y, when X and Y correlated

So I'm trying to show that ${\rm Var}(Z) \le 2({\rm Var}(X)+{\rm Var}(Y))$ for $Z = X + Y$. This seems to be pretty easy to show given that $X$ and $Y$ are uncorrelated. But I'm running into trouble ...
15 views

### Using MANOVA for classification without separating training and test sets

In this study: Rosenblum, Sara, et al. "Handwriting as an objective tool for Parkinson’s disease diagnosis." Journal of neurology 260.9 (2013): 2357-2361 The researchers attempt to classify ...
3 views

### Statistic test on percentage correct classified by emotion recognition

For a potential emotion recognition bachelor-project I was wondering what statistical test I have to perform when I get my results to test whether it's significant. I will be testing which combination ...
35 views

### AIC BIC Mallows Cp Cross Validation Model Selection

If you have several linear models, say model1, model2 and model3, how would you cross-validate it to pick the best model? (In R) I'm wondering this because my AIC and BIC for each model are not ...
47 views

### Coverage Proof of Confidence Intervals

The confidence interval for the mean of a random variable $Y$ has coverage $1-\alpha$ which I am trying to show. Starting from \widehat{E(Y)} - ...