# All Questions

0answers
5 views

### computing mean and sd of d-prime from mean and sd of hits and false alarms

I'm working on a meta-analysis. Some studies report d', others report accuracy (hits and false alarms). I would like to transform all the data into the same measure, d' (also c). However, for many ...
0answers
3 views

### Create age and sexmatched pairs to balance Cox regression further

I analyze ethnic differences in risk of cardiovascular events (CVD) in a cohort study of patients with stable coronary heart disease. I know for several reasons that immigrants should have higher risk ...
0answers
8 views

### tease out significance

Say I have search data like this AvgCost QualityScore SearchShare 3.12 6 0.6364 Where AvgCost is a ...
0answers
14 views

### Can ayone help me in solving the below Problems of probability distribution?

Patients arrive randomly and independently at a doctor's surgery from 8·0 A.M. at an average rate of one in Five minutes.The waiting room holds 2 persons. What is the probability that the room will be ...
1answer
33 views

### Extracting the value of an element from Dataframe in R

I am very new to R and trying to extract a specific element from a data frame and compare it with an integer. I had a table saved in text file. I used the following to read the table. ...
0answers
29 views

### Bayesian probabilty [migrated]

I need to know how to find the Bayesian probability of two discrete distributions. For example the distributions are given as follows: ...
0answers
10 views

### Preparing survey data for analysis

I am preparing a complex survey data for analysis. The survey involved a two-stage stratified cluster sampling. In the first stage, I have 7 strata and 4 sampling units and in the second stage I have ...
0answers
9 views

### R: Is it possible to estimate the poisson noise?

I have a dataset of many discrete counts (RNAseq read counts per base), which contain both real signals and background noise. The noise is random, and should be poisson distributed. What I would ...
0answers
8 views

### Treating multiple observations per object

I am working on a project whose aim is to analyze the relationship between machine elements and their price. My data consists of thousands of machine elements, their price, as well as technical and ...
0answers
4 views

### In-sample likelihood ratio test for losses

Probably a very simple question for practitioners but I am doing this the very first time: I have written a programm for the estimation of a conditional variance model (HEAVY) of return data and an ...
0answers
9 views

### rebuild model based on what columns a record has

I've built a model in R using glm, and in the new dataset that I need to predict, there exist some new levels for the columns that are non-numeric. I know there are so many approaches to deal with ...
0answers
6 views

### Mean squared error / Max error squared

I'm use this metric for variation that is similar to CV, but it is guaranteed to be on a 0 to 2 scale for positive numbers, where 2 is "all over the place" and 0 is "perfectly even". Since its ...
0answers
4 views

### Bias-variance tradeoff in the paired t-test

Suppose we have $K$ subjects and a treatment with two levels, "Before" and "After". A paired t-test is equivalent to fitting a fixed effects ANOVA: $Y = Subject + Treatment$ It is also equivalent ...
1answer
16 views

### R find key influencers

In Excel's data mining tools there is a "Key Influencers" tool which will look at a dataset which is perhaps customers and whether or not they converted to a given goal (e.g. a flag that equals 1). It ...
0answers
8 views

### Using least squares straight line fitting on experimental data with errors

I'm trying to fit a line into a graph with points that have errors both in the y and x directions. I found the following document on the subject: https://www.che.udel.edu/pdf/FittingData.pdf My ...
0answers
8 views

### Identifying the experimental unit

I have included a diagram of an experiment where cells are pooled from multiple animals, cells from the pool are then allocated to different treatments and a measurement is taken from each individual ...
2answers
31 views

### Mean of Poisson distribution experimentally

Suppose I approximate a variable (events of certain type) by a Poisson distribution and I would like to write a program and measure the mean experimentally. The idea is that I have an algorithm which ...
0answers
37 views

### Determining probability distribution for datasets with missing values

As a part of my exploratory data analysis (EDA) prior to further analysis, I'm trying to determine a probability distribution of my pilot dataset's variables. A particular feature of this dataset is a ...
0answers
13 views

### Model selection in nlme's

I can think of four ways to perform model selection nlme's: LRT, AIC, ...
0answers
15 views

### Objective test for proportionality assumption in Cox Regression Model (SAS)?

I was trying to fit Cox Regression (aka Proportional Hazard) model on some cancer data (N=2288). I got the following output from SAS proc phreg: ...
0answers
10 views

### Weka clustering

I ran simpleKmeans clustering in weka version 3.4. I used k=10 and seed=10. The output only ...
0answers
13 views

### Choosing fold size for highly Imbalanced dataset + nested CV + svm

I am trying to classify a dataset with ~1000 points. 90/10 is the class ratio - super imbalanced. Here are the following steps I did: Use 20 relevant features from previous knowledge Remove highly ...
0answers
9 views

### Problem when including code in a macro [migrated]

I don't know if it is the right place to post this, but it seemed to me I would be more likely to get an answer there. Currrently working on SAS for an internship, I am trying to write a macro in ...
1answer
12 views

### Use daily production as a check on whether monthly production goal is likely to be met

This is a real small business problem, not a homework problem. A monthly production goal is 60000. We want to be sure that say 95% of months meet this goal. The goal is a minimum, so we want to be ...
0answers
14 views

### multivariate analysis for time/place where animals are sighted

I have many marked animals that are sighted occasionally. So I have a table with the following columns: Animal DateTime Lat Lon Each animal (about 500) has ...
0answers
35 views

### Determining beta distribution parameters $\alpha$ and $\beta$ from two arbitrary points

Suppose I have two points $(p_1,x_1)$ and $(p_2,x_2)$ where $p_i$ is a probability on the beta CDF and $x_i$ is a value on that same CDF. How would I go about determining the beta distribution shape ...
2answers
13 views

### Paired t-test with subsamples in R?

I've been trying to find a similar "problem", but I didn't, so I'm going to try to explain what am I looking for. I have for different sites A,B,C and D. In each site I have a forest and a fallow=> ...
0answers
8 views

### Sensitivity Analysis for Mulitple Dependent and Independent Variables

I have Mulitple Vectors of Independent Variables and Multiple Vectors of Dependent Variables from a Monte Carlo Simulation. For each Dependent Variable, I want to know the contribution of each ...
0answers
5 views

### R mhurdle with same 2 predictors in 2 separate hurdles

My outcomes are zero-inflated but otherwise normal. I want to propose a model in which the very same predictors determine both whether the value is zero or non-zero, and separately from that, if ...
1answer
15 views

### Estimating Multinomial Multilevel Logistic Models by Binomial models

I would like to fit a multinomial multilevel logistic Model. Unfortunately I couldn't find a package that implements this. I tried Stata's ...
0answers
8 views

### 2 sampled ks test in r

I need to do a two-sample Kolmogorov-Smirnov (KS) test in R, only I don't understand the formulae and how it works when I look it up. I suspect this is because I ...
2answers
30 views

### Confidence intervals which contain 1 but the z test and p value are significant

I calculated the confidence intervals for the regression coefficients using the formula: SE X 1.96. I then took this value away from the regression coefficient to get the lower confidence level and ...
0answers
22 views

### Fit dummies in a Regression

I have a regression specification that consists of a binary dependent variable y, a constant alpha and a dummmy predictor ...
0answers
15 views

### breakpoint analyses on multiple series: how to detect common points

I have 20 time series that span the same period (100 days each), from 4 species sampled at 5 different location. I made a loop to perform a breakpoint analysis on all of them, resulting in 0 to 3 ...
3answers
45 views

### What are the most popular artificial neural network algorithms for recognising the content of images?

What are the most used/popular artificial neural network algorithms for recognising the content of images in general? E.g. If the picture is of a person, dog, cat or a car. If the picture is a ...
1answer
31 views

1answer
15 views

### Logrank test for trend (proportional hazards)

How one can create a logrank test for trend and does it differ from normal logrank test? Any suggestions or literature? Maybe some R examples and functions?
0answers
12 views

### How to find number of samples needed for a 95% confidence interval

I wish to perform a number of tests, what are the minimum number of tests I need to perform to be 95% sure the mean of the test is significant to within ±10% when I repeat the test ? As one example, ...
0answers
6 views

### Carry over effect [on hold]

How to calculate the carry over effect of sales over time. Suppose a brand is having a sale of rs 10 in 2011, 12 in 2012, 17 in 2013 so what will be carry over effect.
3answers
367 views

### Is Baron and Kenny method for mediation now outdated?

Is Baron and Kenny method for mediation now outdated? This is because I got a comment from reviewer saying asking me to refer to Rucker, D.D., Preacher, K.J., Tormala, Z.L. & Petty, R.E. (2011). ...
0answers
6 views

### Repeated measurement model for Dichotomous variable in spss?

I have a repeated data in 7 diffrent time and 4 group. my variable is Dichotomous (yes/no). How I can do it with spss? what non-parametric test could I use? I appreciate your answers Leili
1answer
19 views

### Credit Risk and Concentration

I am working with a UK credit-union and we are looking to build a model to assess our credit risk and changes to this over time. We have a number of loans to borrowers who each have a credit rating ...
0answers
31 views

### Why are these MLE estimates biased?

I estimate the parameters of survival data with censoring which is simulated from Weibull distribution. The mean time to event was set to 10 by choosing the combinations of shape and scale ...

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