# All Questions

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### Does larger p-value for MANOVA necessarily means it is harder to find a “discriminant axe” to classify data? Any expections?

I am new to statistics and currently got a dataset which contains 80 dependent variables and 1 independent variable with 2 groups. MANOVA has a p-value of >0.6 on this dataset. But when I use linear ...
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### pggls function in R - weird results

I need to estimate a panel model. I have run the "normal" fixed effects model using plm in R and also wfe. I also wanted to try pggls considering its tolerance of heteroskedasticity and ...
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### Value function iteration in R [on hold]

Is there any package in R for value function iteration? Matlab is the weapon of choice for this, but I am an R user. I read the vignettes of many packages, but could not find anything that could help ...
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### Auto-correlation calculation

Is auto correlation of lag k the same as auto correlation of order k? If not, how do their formulas differ? For lag k is the denominator: $\sum_1^n(x_t-\bar{x})^2$. For order k is the denominator: ...
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### bivariate normal density function

I know how to show the first part, but I am confused about the second part, how to express the relationship between the two? Any hint, advice or suggestion is appreciated.
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### Can someone provide an proof for $E[P[A|X]] = P[A]$

I'm tired of seeing the word "trivial" for this equality on every single lecture notes I could find online. Can someone please show me why this is indeed trivial? Thank you!
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### How to find probability limits for correlation

I have found that $S=\frac{1-r}{1+r}$, where r is the correlation coefficient follows the F with (n-2,n-2). How we find $P(F_{1-\alpha/2,n-2,n-2}< S<F_{\alpha/2,n-2,n-2}))=1-\alpha$ (This the ...
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### G and R matrices in mixed model and model selection

I have data in which the plants were subjected to four conditions and measured weekly for a month. I would like to incorporate "plot" as a random factor into my linear mixed model using SPSS. I am ...
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### Comparing medians

I am interested in comparing the medians of a continuous random variable across two groups. One option is to do a simple chi-squared test - in stata run median var, by(group). The other option is to ...
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### R code to determine peakedness of a maximum [migrated]

Given input vector $x$, let the maximum of $x$ occur at index $i$ in the input vector. I am trying to quantify the peakedness of this maximum and do that I have thought of determining following ...
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### Distribution of large set of fold changes

My background in stats is limited to a few undergraduate classes. However, I have a question that intuitionally seems to have a statistical answer. Let me describe my intuition first. I do systems ...
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### Simultaneous Score Intervals for Difference of Proportions

In Agresti et al. (2008) "Simultaneous confidence intervals for comparing binomial parameter", it is suggested to use a studentized range distribution with a score statistic. However, exactly how you ...
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### attenuation percentage and confidence interval

I made a logistic regression model 1 (not fully adjusted) and model 2 (fully adjusted; model 1 + covariate A) with Stata. I am trying to calculate the attenuation percentages between OR. I used the ...
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### How to determine a probability that 100% of confidence intervals from a bootstrap contain the true mean

Say I take 500 bootstraps of a population and calculate 95% confidence intervals (CIs) for each sample. I would expect that 95% of the bootstrap sample CIs to contain the true population mean. ...
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### Range of predicted probabilities by logistic regression

I have a binary classification problem with unbalanced classes, e.g. I have 500 examples of negative class(0) and 20 examples of positive class (1) and I need to estimate the probability of positive ...
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### Determining if two profile likelihood curves are significantly different

I want to compare two profile likelihood curves and determine if they are significantly different from one another. For example are the following curves significantly different from one another: I ...
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### PDF of sum of independent Gaussian variables

I am looking for deriving the pdf of $Z$ where $Z= (\sum\limits_{i=1}^N a_i X_i +Y_1)^2 + (\sum\limits_{i=1}^N b_i X_i +Y_2)^2$, where $X_i$ and $Y_i$ are independent, zero mean Gaussian random ...
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### Possible to cross-validate a survival model with right censoring?

Is it sensible and possible to cross-validate a survival model with right censoring? If not, why? If the answer depends on the model, then answer for common survival models like a weibull or ...
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### Significance of a result

Assume you have a working pipeline to achieve a task that looks like: step1 -> step2 -> ... -> stepn -> result. For each of these steps, one can try different methods (functions), but can only see how ...
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### Available Data from a Variety of Distributions

There are several websites and other tools, such as random.org for generating data from either uniform or Gaussian distribution. However, I've been unable to find any such tools for other ...
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### Definition of Scale median

Lehmann, in Theory of Point Estimation p.212 (and also on p.169), defines scale median as the solution to: $${E(X)I(X\le c)} = {E(X)I(X\ge c)}$$ given $X$ is a positive random variable, and ...
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### Can we use the AIC values to compare a hurdle poisson model to a multinomial logit model?

I estimated two different models using an SP survey: Hurdle poisson and multinomial logit with 5 alternatives. My dependent variable is the number of weekly trips (0,1,2,3,4,5 trips) that students ...
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### Fixed effect vs random effect when all possibilities are included in a mixed effects model

In a mixed effects model the recommendation is to use a fixed effect to estimate a parameter if all possible levels are included (e.g., both males and females). It is further recommended to use a ...
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### Is data fusion suitable for this application?

I have a situation where the delay vehicles experience at an intersection can be obtained through 3 or 4 types of sensors. Each sensor provides its own type of data with their own unique ...
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### How is Weka calculating nominal attributes for K-means clustering?

I have both numeric and nominal variables in my dataset. Before applying clustering in Weka, I specified nominal variables to Weka and select K-means clustering. It is good that my nominal data seems ...
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### What to do after calculating Gower for clustering? [on hold]

I used daisy function with Gower metric and found a matrix in R. What is next step for clustering?
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### Introductory texts on structural econometrics

In recent years the structural approach to econometrics compared to reduced form econometrics has become more popular. This involves tight combination of theoretical economic models and statistics in ...
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### How should I evaluate the expectation of the ratio of two random variables?

Let $A$ and $B$ be random variables and $f(A,B)=\frac{A}{B}$. How should I approximate $E(f(A,B))$? I think a Taylor expension may be in order, but I am not sure how to fire it off in this function. ...
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### Systematic Review (maybe) [on hold]

I have 21 paper that different in each study. And all of these are qualitative. for example study 1 : we have 10% good, 25% middle and 65% weak. study 2 : we have 15% very good, 15% good, 45% middle, ...
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### how to Include a useful plot or chart? [on hold]

Respiratory Rates for Children. A high respiratory rate is a potential diagnostic indicator of respiratory infection in children. To judge whether a respiratory rate is truly “high,” however, a ...
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### Best practice for visualizing a lift from zero?

Let's say you have two columns of data. Column A represents a value you had last month, and column B represents a value you have this month. If you want the percent change between the two, you math ...
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### Convergence warnings in glmer

I am running a Generalized Linear Mixed Model in R 3.0.2 using lme4 1.1-7 for a dichotomous outcome variable (success, 0 = no, 1 = yes) ...
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### Data point that minimizes all four parameters [duplicate]

First of all, I must say I'm in no way a data scientist or anything; I just happened to come across a problem, and I am attempting to use statistics to find the best solution. The problem is about ...
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### Why does a confidence interval including 0 mean the difference is not significant?

Could someone please explain why zero being inside or outside the confidence interval tells you whether or not the difference is significant?
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### Linear model / models analysis

Above are three plots of the Linear model I am trying to analyze. The first one is a basic plot of the linear data: ...
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### Classification of time-series data

I am trying to classify some time-series data. I looked at this code from this link: extracting DWT coefficients (with Haar filter) ...
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### Do I subtract end-of-year deaths from total population? (prevalence and incidence)

For calculating prevalence and incidence rates... I am not sure if I should be subtracting "deaths at end of year" from the population total/at risk? I know that incidence rate involves the the ...
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### How do we get/define filters in convolutional neural networks?

How do i obtain filters from convulutional neural network(CNN)? My idea is something like this: Do random images of the input images (28x28) and get random patches (8x8). Then use autoencoders to ...
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### Fitting the parameters of a compound distribution model

I have a set of data $x_{i}$, and I would like to fit a compound distribution probability density function of the form  p(x; \mu, \sigma, \sigma_{\mu}, \sigma_{\sigma}) = \int \int f(x, \hat{\mu}, ...
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### why we need trace plot in MCMC

i am reading papers and i see most of the papers gave trace plots.why we need trace plots in Monte Carlo Markov Chain. what the trace plot of the parameters indicates ?i understand MCMC but i dont ...
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### How to test a claim about a confidence interval (real case)

I need to test a claim made by a company stating that 95% of the cases (passangers per day, peak hour) are processed in 40 minutes or less. 1 - I assume I must collect a passanger sample but how ...
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### Mixed effects structure: Main effects in random slopes with between-subjects design

My question is about whether it is appropriate to include certain random slopes in a mixed effects model with a between-subjects design. This is my first question on this stack exchange, and I'm ...
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### Maximizing Log-Likelihood Estimation for Changepoint Detection

I'm trying to code the changepoint detection algo described here: ...
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### How to assess the functional form of covariates in the Cox model with martingale residuals in R?

I want to find if the functional forms of covariates in my Cox model are linear. I understand the way to do this is to plot the Martingale residuals against the covariate of interest. I have found ...
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### Hypergeometric distribution and its continuous counterpart

I'm modeling an urn without replacement. I'm drawing $m$ balls from an urn containing $p_w$ white balls and $p-p_w$ black balls and I want to know what is the probability that I draw at least $m_w$ ...
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### What options do I have to analyze Non-parametric version of two-factor ANOVA with repetition?

Sorry, my previous question was not very clear I deleted it and am trying again. Question: What options do I have for two-factor non-parametric version of ANOVA with repetition? What is the ...
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### How does the Gower distance calculate the difference between binary variables'?

I have 17 numeric and 5 binary (0-1) variables, with 73 samples in my dataset. I need to run a cluster analysis. I know that the Gower distance is a good metric for datasets with mixed variables. ...
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### How to account for different ratio of samples during training and detection using a support vector machine (svm)?

Consider the following object recognition case: Detection of objects in an image using a sliding window approach in combination with a svm model. During sliding window search using multiple scale ...