0
votes
0answers
4 views

Understanding the CDF of the Exponential from the PDF?

Recently, I was trying to get the CDF of the exponential through the pdf. I know that the relationship between the pdf and the cdf is that the pdf is the derivative $ \lambda exp(-\lambda x) $. But I ...
0
votes
0answers
5 views

Z-test question

Example from wiki: Suppose that in a particular geographic region, the mean and standard deviation of scores on a reading test are 100 points, and 12 points, respectively. Our interest is in the ...
0
votes
0answers
4 views

Predicting value with MLP neural network

I am trying to predict a value using feedforward and back-propagation network but I get incorrect predicted value. I checked the gradients calculation and error is 1.79684799923e-11 < 1e-9 so ...
0
votes
0answers
6 views

Need new strategy for single class classifier

I am attempting to create a single class classifier where the classes are fairly close to balanced (+/- 25). My dataset has ~2,800 samples and ~1,100 features. All of the features are binary except ...
0
votes
0answers
6 views

Estimating parameter of a distribution for some generate random number

I just new in R for solving my statistical problem. Currently I'm working to estimate the parameters of a distribution using 200 random numbers (RN) that I generate using R. I generate 200 RN in 100 ...
1
vote
0answers
5 views

Compare scores calculated for two groups who overlap?

I have three groups of ten children (A, B and C). They are each have different treatments (the treatments are to do with how they are taught about a certain biological feature). Two scores are ...
0
votes
0answers
9 views

Help with interpreting results of simulation

In my homework, we were asked to discuss the results of performing the following do.file in STATA. I don't have a solid grapple with this format, so I wonder if anyone could start me off: ...
0
votes
0answers
8 views

Chance that a vector of observations come from one distribution versus others

My question relates directly to the question at Test to what population an observation came from but I would like to know how to update the information about each possible distribution given ...
0
votes
1answer
9 views

Classification of data with statistics

I have rainfall data series for a particular city. With the help of statistics i would like to classify the data of rainfall into light rain , heavy and very heavy. Is it possible to know the ...
0
votes
0answers
5 views

ANOVA showing 0,00 value while I only want it to show 1 and 2 value

I'm currently working on my bachelor thesis but came across something that I can't fix myself. When running an ANOVA I get the following output: I want to make the 0,00 value gone because now I ...
0
votes
0answers
7 views

Can I get a meaningful false positive rate from an A/~A classifier (ie, with no meaningful true negative count)?

I have an application that basically circles things in images. I need to find the false positive rate. Wikipedia says it's given by (number of False Positives) / (number of False Positives + number of ...
1
vote
0answers
7 views

Survival analysis to model waiting times for buses

I need some way to model what is the expected waiting times when someone can take one of a set of buses, with different time/frequency characteristics. Bus 1 - There are 10 buses an hour, but ...
0
votes
0answers
11 views

Data set generator

I'd like to ask if someone knows a good data set generator for multi-target/Multivariate regression All the best Richard
0
votes
0answers
8 views

One Step Ahead with a forecast horizon of 25

I have 288 data points of the Wolf's sunspot data for the years 1700 to 1987. I need to predict one step ahead forecasts for a forecast horizon of 25. I kept the last 25 data points of the time ...
1
vote
0answers
10 views

Effective sample size for MCMC with multimodal target

I am trying to evaluate an adaptive MCMC algorithm on a multimodal target density. Among other performance measures, I would like to evaluate the sampler in terms of Effective Sample Size (ESS). The ...
0
votes
0answers
5 views

How to add hard negatives to original training data?

I have 2 class binary classification problem with original training data of size N=n_pos+n_neg in general case n_pos!=n_neg but now we can assume that number of positive and negative examples near the ...
-1
votes
0answers
12 views

how to run svm classifier on large data (1500 rows of csv file) in r studio [on hold]

here is the code , but i do not know the first step i.e about data frame ...
0
votes
0answers
16 views

Zero-truncated Poisson model

In the theory of generalised linear models, you may use the exponential family to find the mean and variance of certain distributions. How would the mean and expectation of the zero-truncated Poisson ...
2
votes
1answer
17 views

Correlation between two time-series of unequal size

How can I estimate some measure of correlation between two time-series of unequal size? Is it a good approach to interpolate to the same size? I just want to check for a trend in the values of a ...
1
vote
0answers
7 views

Interpretation of the consistency property of a loss function

I am looking for an interpretation of the consistency property of a loss function used for classification (e.g., the SVM's hinge loss: $V(t)=\max(0,1-t)$). I copy from Wikipedia: Furthermore, it ...
0
votes
1answer
9 views

Kaplan-Meier vs Cox proportional hazards survival estimates

I am conducting a 20 year longitudinal study on firm survival using a number of variable such as size, profitability, cash resource etc. What is the difference between the Kaplan Meier and Cox ...
2
votes
0answers
16 views

Is the Jackknife estimation better than Maximum Likelihood Estimator?

I'm trying to estimate distribution parameters with Maximum Likelihood Estimator (MLE) and Jackknife estimator based on it. The estimation statistic is mean. Jackknife estimator is considered to be ...
3
votes
0answers
13 views

do(x) operator meaning?

I have seen the $do(x)$ operator everywhere in some literature review I am doing on Causality (see, for instance this wikipedia entry). However, I cannot find a formal and general definition of this ...
0
votes
1answer
5 views

Non-linear function optimisation using nlminb function in R

I have been getting error messages in my attempt to estimate parameters in a non-linear function using nlminb function. The following is the code: ...
0
votes
0answers
7 views

In-sample and out-of-sample prediction [on hold]

I am going to forecast delta of profitability (Expected - long-run). I use several estimation : OLS and LOGIT. The approach is cross-sectional, so sustainability is assessed by reference to averages ...
0
votes
0answers
4 views

R lmer error: Model is not identifiable. Error in base::chol2inv(x, …) : 'a' must be a numeric matrix [on hold]

I'm very new to using R, and I've been trying to perform some ANOVA analyses using both lsmeans and difflsmeans via lmer. The code that I'm using was given to me by someone who knows what they're ...
1
vote
0answers
7 views

EM algorithm increase after E step?

It might be a silly question, but here it goes. The short version of my question is whether the marginal likelihood calculated after every E steps should be increasing or not. More details: Using ...
0
votes
0answers
16 views

help with a statistic question. I did most of the work. (null hyothesis) [on hold]

Can someone help with these questions. I did majority of the work. but some i need help with. Are the mean number of times a month a person eats out the same for whites, blacks, Hispanics and ...
0
votes
0answers
5 views

What statistical test can I use to compare the fluctuation of a feature over different datasets?

I have a recording of an instrument that can be divided into N sections (scale, single notes, music excerpt and so on). For each section, I divide the signal into short frames and I extract a value ...
0
votes
0answers
17 views

Inverse gamma posterior

I am working on bayesian analysis and I have a normal likelihood function and an inverse gamma (IG) prior for the parameter $\lambda$. I have the following posterior: $$ \propto ...
0
votes
0answers
7 views

Modelling Length of Hospital Stay, Poisson Regression or Survival Analysis

I would like to find out what people thought about the better or more widely accepted way to model hospital Length of Stay (LOS) is? LOS can be thought of as count data (number of days) with a ...
1
vote
0answers
5 views

dividing a multiply imputed dataset into derivation and validation cohorts

R/statistics noob. Mac OSX 10.11, RStudio 0.99.842. I'm developing a clinical prediction tool as part of my PhD. I have missing data (23k cases, 24 variables, 70% of variables have at least one ...
1
vote
1answer
8 views

How to calculate variance contribution in a Zero-Inflated Poisson regression?

I was wondering if anyone has an idea on how to calculate the contribution to variance of each independent variable in a Zero-Inflated Poisson. How would it even work if you actually have two models ...
1
vote
0answers
29 views

Maximum Likelihood Estimation of Coefficients for Linear Regression Model

I am reading up about using Maximum Likelihood to estimate the parameters of a linear regression equation. I came across this video (https://youtu.be/_-Gnu498s3o) and I thought it explained it very ...
0
votes
0answers
7 views

How to compare two test according to power?

I know the expectation calculates the power of the test, but how can i find a test that is as good as the given one based on the power?
0
votes
0answers
12 views

Linear Regression for Forecasting: what are the risks?

I have a dataset containing financial data of multiple firms on 7 to 10 years. (yearly data). For each firm/variable i want to predict its value in the next two years. I don't have enough data (7 to ...
1
vote
0answers
17 views

Is/are there any threshold value(s) to determine to see if PCA is useful at all, specially for high dimensional data?

Apologies if this is a naïve question, but it's not so naïve to me! Let's first assume we have 2D data which are perfectly linear but not along the x- or y-axis. PCA will rotate it so that it becomes ...
0
votes
0answers
3 views

Difference of means in 3 dimensions (Hotelling's T^2 for 3 dimensions or equivalent)

I am trying to determine if two groups are different in 3 dimensions (3 variables). I am looking for something similar to Hotelling's T^2, but for 3D instead of 2. I have two groups 'Known Color' and ...
0
votes
0answers
5 views

Revenue Forecasting using Markov Chain or Queuing Theory?

I am trying to forecast revenue for a HealthTech giant that sales HealthTech Hospital Equipment like Ultrasound, Magnetic resonance, CT AMI etc. The nature of business is Build to Order, which means ...
0
votes
0answers
22 views

Effect of ignoring correlation between studies providing data for multiple comparison on the meta-estimate

I am addressing reviewer comments on a meta-analysis paper I performed on mean gastric pH in fed and fasted states. Some literature studies included in the meta-analysis provided data for multiple ...
0
votes
0answers
13 views

Google correlate - data transformation / switching positive / negative correlation

Google correlate Takes your data and then searches for positive correlations in search terms. From my understanding it returns search terms that positively correlate to your data. For example if ...
0
votes
0answers
16 views

How to prove it?

Under $P$, the random variable X has a double exponential distribution with positive constants, $r_1$,$r_2$,$p$,$q$ such that $p+q=1$, with the probability distribution function given as: ...
-1
votes
0answers
16 views

Can any arbitrary function be approximated by a rational function?

To add a little more clarity to the title, can all functions be approximated by some rational function within a particular domain? I'm interested in the potential applications for machine learning. ...
1
vote
0answers
28 views

Hypothesis testing with no sample or standard deviation, is this is a trick question?

The question I was asked is as follows: A website received 6802 page views last week. Does this provide evidence at a 1% significance level against the claim that the website receives on average 1000 ...
0
votes
0answers
32 views

Covariance Between $\hat{\beta_0}$ and $\hat{\beta_1}$

Our model is $Y=\beta_0+\beta_1X+U$. We know that $\hat{\beta_0} = \beta_0 + \sum\limits_{n=1}^N c_nu_n$ and $\hat{\beta_1} = \beta_1 + \sum\limits_{n=1}^N k_nu_n$, where $$k_n = ...
1
vote
2answers
191 views

Do p-values assume an unlikely event has already happened?

According to this thread What is the meaning of p values and t values in statistical tests? a p-value essentially lets me compare the probability of tail-end (unlikely) events occurring and judging ...
0
votes
0answers
12 views

Practicality of James-Stein Estimator

It is well known in the literature that for a $d-$dimensional gaussian random variable, James-Stein estimator has a lower mean-squared-error than the 'ordinary' sample-mean estimator (for $d>2$). ...
1
vote
1answer
16 views

In a random forest algorithm, how can one intrepret the importance of each feature?

I am in the process of building a Random Forest algorithm in MATLAB using the TreeBagger function. In the documentation, it returns 3 parameters about the importance of the input features. My ...
-1
votes
0answers
10 views

Set all values of a column to zero conditionally by factor level

I am trying this in R I have the following variables in a data frame: X1 (numeric) X2 (numeric) ... X100 (numeric) X101 (factor with 5 levels) X1 to X100 are numeric I want to do the following: For ...
1
vote
0answers
9 views

Model for count data with different exposure time (some times are terminated by death)

I am looking for most suitable model for count data in the following case: we collect number of patient's visits in a hospital for $t_i$ days ($t_i$ varies across subjects) some patients died ...

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