2
votes
1answer
47 views

Interpretation of this heatmap

Consider a synthetically generated dataset. Assume we have two groups of people, one is given diet pills, the other a placebo. Their weights are measured at 4 different days, namely, ...
2
votes
1answer
70 views

Does this look like a Cauchy distribution?

This is my data there is more actually... but I just want to know if this looks like a Cauchy distribution, such as these: I'm asking about just that bump... here is the whole distribution , ...
0
votes
1answer
30 views

Generating data from Probit regression, cut off 0 and variance 1 necessary?

I am trying to create a dataset using a Probit regression model in R, where I have an intercept and three covariates. I first fix a set of coefficients for the three covariates, generate these ...
0
votes
0answers
5 views

Repeated measures ANCOVA - heterogeneity of slopes

In my 2x2x2 mixed model ANCOVA, the covariate is interacting with only one of the main effects (repeated measures). Would it be OK to interpret the rest of the effects and interactions (which were not ...
0
votes
0answers
6 views

How many number of items should i include in my test?

I have designed two post test ,a recognition test and a production test.I have inserted 18 items in each test. As I sifted through articles , I 've read that we should include at least 30 items to get ...
0
votes
1answer
29 views

Does a lower t-stat suggest better evidence for rejection? [duplicate]

Say I have these two models: $y = \beta_0 +\beta_1x_1 + u$ $y = \beta_0 +\beta_1x_1 +\beta_2x_2 + u$ and the $p$ value for $H_0:\beta_1 = 0 $ with $\alpha = 10\%$ for both is less than 0.001, but ...
1
vote
1answer
45 views

Why report r-squared in Instrumental Variables Estimation?

I mean the the R-squared calculated such as in $R^2=1-\frac{RSS}{TSS}$ when you use the $RSS$ from the original structural model and not recalculation that you should do in order to do an F test. With ...
0
votes
0answers
6 views

Help in state and parameter estimation when a time series model excited by pseudo binary input

An IIR system is excited by a pseudorandom binary signal $z_n$. The output of the system is corrupted by zero mean additive white Gaussian noise and this is observed, i.e., $y_n = \mathbf{h^Ty_{n-1}} ...
1
vote
0answers
8 views

Akaike information criterion for categorical and numerical data

How should I compute AIC for categorical and for numeric variables in classification problems? I see in Chapter 6 of Zumel and Mount that they use AIC before they train classification algorithms ...
1
vote
1answer
16 views

Alternative to AIC for feature selection in classification

I want to know what are the most common methods for feature selection in classification problems (binary and mutli-class). I see in Chapter 6 of Zumel and Mount that they use AIC before they train ...
1
vote
0answers
16 views

Count Data Model, Poisson Distribution and Rounding?

In doing a count data model using a Possion distribution, should the estimate (output) be rounded (or the ceiling) if your target variable is always a whole number in the input training target data ...
0
votes
0answers
12 views

Scatterplot with two different categories of data [duplicate]

I have a text document containing three columns. One column is "sex", and each value is either "M" or "F". The other two columns contain numerical data (my explanatory variable and response ...
0
votes
0answers
11 views

Time series analysis for discontinous years

i have a data of measured values of pH in river water for two years 2004 and 2009 for each month. I want to see seasonal trend ie: are there similarity in summer , winter and monsoon for both year. ...
0
votes
1answer
26 views

Transforming Negatively Skewed Independent Groups

I have two independent groups, (roughly 30 in each) – and their performance on 3 different tasks, there are 10 scores in total for each group. The majority of them are negatively skewed so I know I ...
0
votes
0answers
3 views

Possible Stacking Orders [migrated]

I have a question about how to calculate the total number of stacking combinations possible given a set of constraints. Specifically, imagine I'm trying to make a linear stack of objects ...
1
vote
1answer
45 views

What is the reason for this discrepancy between confidence level and probability?

I ran the following R code: library(Hmisc) binconf(x=1, n=70) # PointEst Lower Upper # 0.01428571 0.0007327613 0.07658187 Which is the ...
2
votes
0answers
50 views

How to score predictions in test set taking into account the full predictive posterior distribution?

I have three predictive models (regressions) which parameters are estimated by Markov Chain Monte Carlo. Predictions are made over a test set of size $N$. Since I compare the models under different ...
0
votes
0answers
11 views

The probability of m out of K things being wrong with an error of ɛ

I have a homework question about a machine-learning algorithm that uses ensemble learning with simple majority voting. Assuming we have K hypotheses, each with an error ɛ, the question asks us to ...
2
votes
0answers
14 views

Choosing a line/plane to seperate two classes of binned data

In high energy physics I know it is common task to find the best separation point between two classes of binned data, usually signal and noise. This separation point is determined by making a ...
1
vote
0answers
26 views

Incorporating intraday data into end-of-day forecast

my target variable is observable intraday but I am interested only in EOD forecasts. I will denote the variable $\ y_{D,24}$ as the reading of interest for day D is ...
0
votes
0answers
4 views

Removing contrast effect in mixed modelling deletion test

I am doing a mixed, linear regression analysis and now want to conduct a series of deletion tests on my max model, where I test if there is a significant increase in deviance once an effect that binds ...
1
vote
0answers
42 views

An 'easy' exercise on conditional expectations and filtrations

I am struggling with the following exercise in the context of modeling information structure via filtration to evaluate contingent claims. I hope that someone can explain me how to derive the ...
1
vote
0answers
24 views

Paired homogeneity test: Compare two regression coefficients in R

I have a question about paired homogeneity test. By using Cox regression analysis Im evaluating 2 new biomarkers (A and B) in association with a outcome (X). I developed 2 multivariable models and on ...
3
votes
0answers
30 views

Modelling flight delays with negative values

Modelling flight delays with negative values I am working on a model to predict whether a flight will be delayed. The data consists of some explanatory variables for flights from a specific airport. ...
0
votes
0answers
38 views

Multiple imputation of conditional variables

I need to impute the missing values of a dataset of medical data in which several variables only make sense if another variable has a specific value. In the questionnaire the data come from they were ...
1
vote
0answers
16 views

partial plots from a Random forest classifier for binary predictors

I'm working on a classification problem with continous and categorical predictors with Random Forests (RF). I'm particularly interested on RF as we avoid the specification of the functional form. ...
5
votes
2answers
117 views

Which distribution to use for a probability problem?

In a food processing plant, on average, 2 packaging machines breakdown per week. I let x be the number of processing machine breakdowns in a week. So x is Poisson(2), but one part of the question ...
1
vote
0answers
10 views

should we check for multicollinearity when building a discrimination analysis?

In fact, I have two questions: 1- do we need to check for the multicollinearity when we deal with linear discrimination analysis? 2- how to solve those variables which are multi-collinear? Lets ...
0
votes
0answers
10 views

How libsvm performs Cross Validation?

I wanted to know that whether libsvm performs cross validation by preserving the class ratios / label distribution within each fold? My train data is organized. For example if I have 20 training ...
2
votes
1answer
15 views

Advantages of counterbalancing vs. randomizing stimuli

I'm designing an experiment, in which 40 participants answer 10 questions, 5 in condition $A$ and 5 in condition $B$, and I'm interested in the difference between the two conditions. It's not clear ...
1
vote
0answers
26 views

Is sampling according to several i.i.d. random variables or to just one of them equivalent

Suppose we have n+1 random variables i.i.d. distributed $X_0,X_1,...X_{n}$. Is it the same operation if I generate n samples according to $X_0$ $\{S^0_1,S^0_2..,S^0_n\}$, or if I take from each of the ...
1
vote
1answer
28 views

structural break

Say I have the equation: $y_t = \alpha + \beta*\text{time}$ I'm looking for a structural break test that allows both parameters ($\alpha$ and $\beta$) to potentially change with a structural break. ...
1
vote
1answer
14 views

Data visualization tips for a 2x2 factorial design

The data stem from a 2x2-factorial design where both factors have two levels. The x-axis shows the words of a sentence and the y-axis the mean reaction time for each single word. Here is how I ...
-1
votes
0answers
33 views

Optimal brain damage in R [on hold]

Is there any R package implementing optimal brain damage algorithm or anything similar what can be used to prune neural networks models?
2
votes
1answer
23 views

Can I apply factor analysis on multiple choice questions?

I am looking to validate a questionnaire and would like to know if I can use factor analysis on the multiple-choice questions (MCQ). Also, I have another section where I am asking about participants ...
1
vote
0answers
18 views

Treatment of mixed effect models for Box-Cox transformation

To analyse the Box-Cox transformation in a mixed effect model, no simple transformation/ code in R exists. So which of the following approaches would be valid ways and why? 1) Take a random sample ...
2
votes
0answers
17 views

Creating a copy/simulation of a dataset respecting statistical properties?

I often need to work with and analyse electronic medical record data which cannot be moved from the servers in the organisation where it resides, due to ethical reasons. Is anyone aware of a method or ...
1
vote
0answers
26 views

When to use Bayesian Networks over other machine learning approaches?

I expect there may be no definitive answer to this question. But I have used a number of machine learning algorithms in the past and am trying to learn about Bayesian Networks. I would like to ...
0
votes
0answers
40 views

Setting up a aov model in R for a variant of a 2-way nested ANOVA

I have a rather complex experiment i need to analyse The experiment was an infection trial, where the effect of two different infection methods ("inoculation" and "in-contact infection") were ...
3
votes
1answer
39 views

Should I use Mean Square Error or Classification Rate?

I am a self-taught person and I would like your help. I am learning about predictive modeling in general, and I'm also trying to do predictive modeling for a specific problem. I am exploring ...
0
votes
1answer
17 views

Can we boosting or stacking with different input variables for each model in machine learning?

I have a question about Boosting and stacking in machine learning. Suppose that I will train neural network, SVM and logistic regression using optimization algorithm to optimize best inputs in first ...
0
votes
0answers
17 views

Fisher's linear discriminant VS naive bayes

i know some basic things about linear classifiers. i prefer two think geometrically about them. and what'll happening if covariance Matrix were different things. Generally; What's the difference of ...
0
votes
0answers
17 views

Clustering MVT response data by audience

We are doing multivariate testing 4 possible values for each of 3 variables on a landing page: (a) offer presented, (b) product claim message displayed and (c) image used. So, 12 dummy variables, 64 ...
-2
votes
0answers
23 views

Statistically prove that answers to questionnaire are not correlated to questions

I have a questionnaire of 4 "yes-no" questions: A1,A2,B1,B2. The correct answer for A1 and A2 is "yes", and the correct answer for B1 and B2 is "no". I need to statistically show the fact that ...
0
votes
0answers
11 views

Correlation between decision trees

How do you find the correlation between decision trees? I know this is an issue when working with random forests, but I can't find an explicit formula anywhere. I only get that random forest reduces ...
0
votes
0answers
15 views

Interpreting partial eta squared and reporting it apa style

How do you interpret and report partial eta-squared in a two-way anova? I have run a two-way anova to inspect whether gender and level of education interact to have an effect on positive affect. ...
0
votes
0answers
13 views

software or libraries to create document term matrix for arabic texts? [on hold]

Ideally I would like to analyze arabic texts without translating. Does anyone know any software or libraries for R or python that can make a document term matrix out of Arabic texts? Thanks.
1
vote
0answers
20 views

QQ plot in Python

I generated a qq plot using the following code. I know that qq plot is used to check whether the data is distributed normally or not. My question is what do the x and y axis labels indicate in qq plot ...
0
votes
1answer
23 views

What do you mean by pollster bias in an election?

I came across harvards election poll data science question. I which they ask: Is there a pollster bias in presidential election polls? What exactly is a pollster bias? can some one explain it to me in ...
-1
votes
0answers
9 views

statistics test to use with ordinal data [on hold]

If a group of people come into a room in a given order one day and we compare with the same group of people coming into the same room on another day and they enter in a different order. Each person is ...

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