# All Questions

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### When to use ANN with tensorflow?

I'm new to machine learning and tensorflow and I'm confused as to why (and when) to use the types of ANN (ie recurrent neural network) with tensorflow? I know RNN is good for sequences of data/time ...
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### When to include or reject correlation term in two variable linear regression

I am studying a treatment that degrades device quality and performed an independent sample test on two batches that had different initial quality. I analyzed the data with a two variable linear ...
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### If the fitted hazard ratio from a Cox model is approximately 1, does that mean the covariate is not significant?

Does a hazard ratio nearly 1 indicate that the covariate's effect on survival time is 0? If so would the corresponding p-value routinely indicate statistical insignificance? In other words, can a ...
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### Setting specific values on the X axis when using ggplot

I am trying to plot a graph showing the number of events at the Olympics as a function of the year that a specific Olympic took place. My data frame is called ...
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### Using nlsLM() for importance sampling for pricing european optoins

I am trying to implement a method for finding an optimal drift in pricing European options with importance sampling using this article. The article in pages 489-490 suggests to use Levenberg-...
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### Determine if a time-dependent Cox model is appropriate

Before the description, here are my questions (1) Is the set-up of my time-dependent data correct? (2) Are the ways I run my Cox proportional hazard model with a time-dependent variable/ non time-...
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### Basic Proability Doubt

I have a basic probability doubt. If I have 5 different vehicles backstage, out of which 3 random can be showcased to the public. What is the probability of each vehicle to get to showcase? Once a ...
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### Expectation Value of Standard Deviation from “k” Closest Samples

The question that I'm am trying to answer is how to determine the expectation value of the standard deviation of 'k' closest samples to value 'A'. The standard deviation and mean of the underlying ...
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### Correlations computed within subject vs collapsing across subjects

I have model predictions (x) that I want to test against subject ratings (y). There are 20 stimuli per subject and I have data from 30 subjects. What I did initially was to collapse all (x,y) pairs of ...
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### How to model my data with linear mixed models for contrasts analysis

I have a dataset containing one dependent variable which is the concentration of antibiotic needed to kill a bacteria, which was measured for several different antibiotics for three different ...
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### Sample weights? [on hold]

Aim of study was to know the prevalence of disease. Using PPS sampling 30 clusters were selected. From each cluster 40 individuals were expected. Few clusters have less than 40 individuals while few ...
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### visualization of two sets of confidence intervals in a scatterplot

I am seeking some general ideas on how to more effectively present two sets of confidence intervals in a scatterplot. There are a total of 10 point estimates and the associated 20 CIs, 10 on each ...
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### U or Inverted U shaped relationship in count data models

Some scholars test for curvilinear (U or inverted U shaped) relationship in nonlinear models such as Poisson and negative binomial. Please clarify 1) Isn't the relationship between a predictor and a ...
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### How to generate heteroskedastic data for linear regression analysis given Y

I have at m different points on a surface representing an organ n measures of a organ property for n subjects (such as wall thickness). These values have been stored in a matrix Y with m columns and ...
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### Apply word embeddings to entire document, to get a feature vector

How do I use a word embedding to map a document to a feature vector, suitable for use with supervised learning? A word embedding maps each word $w$ to a vector $v \in \mathbb{R}^d$, where $d$ is some ...
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### How to measure if data conforms to logarithmic curve

I am collecting data that should closely resembles a logarithmic curve. I have many datasets. How can I measure how closely each dataset resembles a logarithmic curve and call out any outlying ...
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### How to model variability within timepoints when DV is a proportion per timepoint

(Edited question) I am looking at some quality improvement (clinical) data.... I have a dichotomous outcome over time - subjects either experienced or did not experience the event in question. I have ...
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### Forecast (R) with Trend, Seasonality and Promotions (Causals)

I have aggregated sales data along with price discount at month level for two years. There are seasonality, trend and also causals - the impact of price promotions (discount, in percentage). I want to ...
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### Is stagewise feature discovery an invalid approach?

Suppose we want to build a regression or classification model. However, the features (independent variables used) are not all ready at one time. This is very realistic in business, because the data ...
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### Variable Importance's reliability when model accuracy is low

I am trying to predict the termination events for a company. I also want to rank the most important variables that lead to termination. I ran a decision tree model and have the following questions: ...
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### What is the proper inter-rater reliability analysis for continuous count data?

I'm analyzing a study where participants needed to list as many plausible solutions to a given question. There are two raters who are counting the number of plausible solutions, what is the best way ...
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### How to put nested random effects and crossed random effect together inside in a nlme model?

In my model I have few covariates. Also I want to include the random effects state, county and ...
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### Classification modeling on data with several levels of grouping [on hold]

I need to create a classification model on data with several levels of grouping. The data looks like the below graphic. I have TV data where in for every house I have several TV devices, each TV ...
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### Calculate relative standard error with binomial proportion?

If one has a rule that says, do not report an estimated mean if its relative standard error exceeds 30% as that estimate is considered "unstable,"[1] how does one deal with a binomial proportion? For ...
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### Results of Softmax regression on MNIST dataset

I'm currently following this lesson: http://ufldl.stanford.edu/tutorial/supervised/SoftmaxRegression/ , and after I coded their equation I got: ...
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### How to tune hyperparameters for LLE?

I'm running LLE using Scikit-Learn (with the LocallyLinearEmbedding class), but there are a few hyperparameters and I would like to use grid search with cross-...