0
votes
0answers
2 views

Is the covariance of standardized variables the correlation?

I have a basic question. Say I have two random variables, $X$ and $Y$. I can standardize them by subtracting the mean and dividing by the standard deviation, i.e., $X_{standardized} = \frac{(X - ...
0
votes
0answers
2 views

Hyperparameters and grid search with log2 values?

Why grid search for tuning hyper-parameters such (C-gamma for RBF SVMs) are usually performed over logarithmically spaced values (such log2 values)?? Thank you so much!
0
votes
0answers
7 views

Multiple Regression with Predictors that Restrict other Predictors

I'm not even sure if the title of my question makes sense at first sight, so let me try to explain it. I'd like to fit a parametric multiple regression model to data. But depending on the value chosen ...
0
votes
1answer
13 views

Best ways to model 'big data' given limited computing resources

Suppose I have a large data set(10 GB), with a response variable and multiple independent variables. What is the best way to utilize the data to build a model on? If the full data set includes 10 ...
0
votes
1answer
9 views

An example of Instrumental Variables use

In the following example of Green's Econometric Analysis, he writes at a certain moment: «If the number of weeks worked, and the accepted wage offer are determined jointly, then $ln Wage_{it}$ and ...
0
votes
0answers
2 views

Use of VIF to eliminate redundant explanatory variables used in separate models

I'm currently conducting a study examining the effect of early reproductive success (ERS) in female mountain goats on longevity. I have several definitions of ERS that will be used in separate ...
0
votes
0answers
6 views

Logistic model cross validation error in SAS

I am using sas and want to fit a logistic regression model to predict the prob of long male life and construct a 2*2 table for cross validation rate. But I don't know why my code does not work. ...
0
votes
0answers
6 views

Restricted Boltzman Machine , contrastive divergence

I have a difficulty with understanding contrastive divergence. I know that there are positive and negative phases. Let's say I have visible vector v = [v1,v2,..bv] where bv is bias. I have also matrix ...
2
votes
0answers
11 views

Kurtosis of linear combination of independent variables

Dear fellow statisticians, mathematicians, I struggle to find proof of one seemingly simple statement. I would be very grateful for any help, I am quite desperate finding the proof. I thank you very ...
0
votes
0answers
13 views

Non-significant interaction effect

I currently have a regression where adding an interaction effect between two significant variables (a float and a boolean) makes them non-significant. Given that this interaction effect is not ...
0
votes
0answers
2 views

Conditional transition matrix (consistent estimates)

Is there a model/technique that is able to estimate transition matrix (which would be consistent, i.e. sums of their rows would be always 1) conditional on some continuous variable X? Let's say I ...
-1
votes
0answers
12 views

How do i find the P-Value of the this question using TI-83?

In a clinical trial 23 out of 875 patients taking a prescription drug complained of flulike symptoms. Suppose that it is know that 1.5% of patients taking competing drugs complain of flulike symptoms. ...
0
votes
0answers
17 views

Quantifying how uniformly spread out points are?

I'm looking for a way to quantify how "clumped" vs homogeneously/uniformly distributed points are in a graph. Each collection has 100 points as (x,y) pairs. I've attached two graphs as an example. ...
1
vote
0answers
8 views

Testing interactions with non-normal ordinal data

I am testing a hypothesis in which my scale DV (PSS) is predicted by an interaction between an Ordinal DV and a scale IV. The ordinal IV is TF (Total Freq) The scale IV is and PQM (Practice ...
0
votes
0answers
6 views

Datasets with a specific decision structure [on hold]

I'm looking for classification datasets where the prediction variable has a certain structure, i.e. if the possible prediction outcomes are natural numbers between 1 and 10, the user is more preferred ...
0
votes
0answers
36 views

Understand data scientist's responsibilities

Is there anyone who can help me to understand more in depth the data scientist's responsibilities: Responsibilities (use data and build models to): Discover the customer, rediscover the ...
0
votes
2answers
23 views

statistical prediction

I am new to statistical methods so this question may be very simple for you. I want to know some "statistical prediction methods" for a sequence of numbers. The numbers may represent financial or ...
1
vote
1answer
16 views

Prediction uncertainty intervals for predictions of machine learning algorithms

Assume I have a regression problem. I fit models on a train data set and tune their hyperparameters using CV. I then run the models on the test set. What is the best way to calculate prediction ...
1
vote
1answer
11 views

out-of-bag error estimate for Boosted Trees

In Random Forest, each tree is grown in parallel on a unique boostrap sample of the data. Because each boostrap sample is expected to contain about 63% of unique observations, this lefts roughly 37% ...
0
votes
0answers
13 views

Standard deviation error bars and kruskal.test in R

I need to test if there is a significant difference between two groups of data, each with three replicates. (Multiple groups) I used the following approach: ...
0
votes
1answer
23 views

Histogram in R from two vectors

how can I create a histogram in R from known values and counts? Thing is, I need to change manually h\$counts in my data set, so I have no data for that new histogram with changed values in h\$counts. ...
0
votes
1answer
29 views

Algorithm to find common sequence

Assume that "1,2,3" are the ids of users, active means that person visited the stackoverflow in last one month (0=passive, 1=active), and there are positive and negative votes. ...
0
votes
0answers
12 views

Variable selection via mutual information

I am building a SVM model and was wondering whether filtering variables based on mutual information between response variable(binary 0/1 variable)is a good approach? Also, would the condinformation ...
0
votes
1answer
14 views

How to return all a particular column in a data frame

Suppose I have a data frame mysample. When I try to access only the second column using mysample[,2] I get a single element. How do I return the second column of the data frame?
0
votes
0answers
9 views

Correlation/association for categorical and interval data [duplicate]

I am testing data for correlation. The outcome variable is categorical with 8 categories. There are 20 predictor variables, some are categorical and some are interval. The questions are Is there ...
0
votes
0answers
9 views

Econometrics - Relationship between cointegration and ECM

I'm pretty new to econometrics and I've been taking a class at University which uses the book "Econometric theory and methods" by Davidson and MacKinnon. It's a pretty good book but there's one thing ...
-1
votes
0answers
13 views

How do you do a log-linear analysis in r?

I can't seem to find anything on log-linear analysis. Does anybody know how to do them in r? I have two variables: one a dependant one (yes or no recoded as 1 or 0) and an independant one with 5 ...
0
votes
0answers
5 views

Isomap and Local MDS- embedding to linear spaces or not?

In Section 14.9 [1], it is said that Isomap and LocalMDS are embeddings into non-linear manifolds. The embedding is clearly a non linear operation, thus worthy of being NLDR. But As both Isomap and ...
0
votes
0answers
7 views

How to check if a sample is representative or not biased?

We are studying the difference in behavior between genders on an online community. We are only interested on those users who participate in the site and whose gender could be easily inferred by other ...
0
votes
1answer
20 views

Pearson's Chi Square test (Goodness of fit)

I have two arrays that I would like to do a Pearson's Chi Square test (goodness of fit). I want to test whether or not there is a significant difference between the expected and observed results. ...
0
votes
0answers
8 views

Which offers better performance, RJAGS or PyMC? [on hold]

I've looked around for some benchmarks, but have not found any. Do any of you know which runs faster: JAGS or PyMC? I have a model in R, but would like to know if PyMC would run faster, and what ...
0
votes
0answers
16 views

Which one is correct phase for neural network or support vector machine? Features or Inputs?

Which one is correct phase for Neural Network or Support Vector Machine? Features or Inputs? Based on ...
1
vote
0answers
5 views

reference for regime shifting models

In looking for a good introduction to regime shifting models. It would be nice to see things like simple example of regime shifting models, ways to detect a regime shift in data, fitting regime ...
0
votes
0answers
3 views

recurrence quantification analysis

I am relatively new to the use of recurrence quantification analysis (RQA) is a method of nonlinear data analysis which quantifies the number and duration of recurrences of a dynamical system ...
0
votes
0answers
6 views

JAGS dmstate markov specification

Does any one have experience in running multi state models in jags? I am trying to run a msm on my dataframe with activity being 1/0 time from diag being times observation of the activity and patient ...
0
votes
0answers
5 views

using both raw and weight of evidence values in logistic regression

I am building a logistic regressin model for probability of take-up for a lending product. I have a number of continuous variables. In the past, I have always used EITHER weight-of-evidence ...
0
votes
0answers
7 views

Confidence interval odds-ratio matched case control

Consider having a list of pairs of binary data denoting observations from a matched case control study. The list may be used to set up a contingency table and an odds-ratio can be calculated by ...
1
vote
0answers
7 views

Relative advantages of nnet, neuralnet, caret and RSNNS packages

What are the relative advantages and disadvantages of different packages available for neural networks: nnet, neuralnet, caret and RSNNS? Which is best in terms of simplicity? Which is best for ...
0
votes
1answer
17 views

Pros of back propagation learning algorithm

I'm doing some research into neural networks and it seems like every single one i've come across implements a back-propagation algorithm. Is this because they're very easy to implement or are there ...
0
votes
1answer
26 views

Distribution of the stddev of movie ratings

I have a database of 10-star movie ratings (similar to IMDB). For each movie the raw data is a distribution of votes from 0-star all the way to 10-star, and I have also computed the mean and standard ...
0
votes
1answer
29 views

How to randomize order by sets in r? [on hold]

I need to randomize a list of words by sets. I have a list of 5 pairs of words and in each pair there are two words: one word in position 1 (1w1) and another word in position 2 (1w2). These pairs are ...
0
votes
0answers
12 views

How to check for confounding factors

I have been doing an analysis using a difference in difference setup. In my raw sample I OLS and first difference (two time-periods) I get the effect that I would expect. Namely that shocks in the ...
1
vote
1answer
21 views

positive price coefficient after instrumentation in demand estimation

I need to complete an assignment for Industrial Organization course where one of the tasks is to estimate a discrete choice demand model. This means I basically need to estimate a linear model: ...
0
votes
0answers
17 views

Proving conditional probability sequence using the sum rule

Given the probability: $$p(a,b,c)=p(a)p(c|a)p(b|c)$$ How to prove $$ p(a,b)=p(a)\sum_{c}p(c|a)p(b|c)=p(a)p(b|a) $$ Does anyone have idea how to prove the above sequence? I am confused how is the ...
1
vote
0answers
22 views

Method for fitting censored data in R

I have 320 data points - each has a redshift and a turnover-frequency, and I want to fit a correlation between them (a linear fit). However, 120 of the turnover-frequency values are upper limits. As ...
0
votes
0answers
9 views

How to make zero-mean random noise with standard deviation equal to 1?

Now I'm trying to make a equation within MATLAB. the equation which is zero-mean random noise with standard deviation equal to 1 How to make zero-mean random noise with standard deviation equal to 1 ...
0
votes
0answers
8 views

problem with fitting ARMA (1,1) to a road accident data using mintab [on hold]

MONTH OBSERVATION J 2 F 0 M 1 A 4 M 1 J 2 J 5 A 1 S 0 O 2 N 1 D 4 J 4 F 1 M 3 A 0 M 0 J 0 J 3 A 2 S 1 O 6 N 5 D 3 J 4 F 3 M 1 A 1 M 1 J 2 ...
0
votes
0answers
16 views

Any R packages for mixed logit or probit? [on hold]

I have choice data sets and choice is decided within pairs (Choice A or B). If I have 100 pairs and each pair has each decision values but each pair has different situation, I would need to use mixed ...
0
votes
1answer
17 views

De-normalizing Google Trends data?

Does anybody have suggestions on how to de-normalize Google Trends data? The site says that their trends are made with the following metric: The numbers on the graph reflect how many searches ...
5
votes
2answers
48 views

How to find weights for a dissimiliarity measure

I want to learn (deduce) attribute weights for my dissimilarity measure that I can use for clustering. I have some examples $(a_i,b_i)$ of pairs of objects that are "similar" (should be in the same ...

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