# All Questions

134,601 questions
19 views

### Chi Square - alternative for three-way interaction

I am interested in the effect of predictability and expected value on the choice between two payment options. Basically, I have a 2(predictability of the payment option: predictable vs. unpredictable; ...
17 views

### Can a trained neural network recognize rotating characters? [duplicate]

Suppose I have a trained neural network that can recognize, for example numbers from 1 to 10, the size of the picture $28 \times 28$. I made the rotation of these pictures by 90 degrees. Does now ...
9 views

### how can i figure out my z statistic value is significant or not in two-step GMM?

topic: FOREIGN AID, CORRUPTION AND SUSTAINABLE DEVELOPMENT IN DEVELOPING ECONOMIES:A PANEL DATA ANALYSIS firstly i face higher value of z-statistics, my teacher told me it should be greater than 1.67 ...
19 views

### Symmetric probability density function proof [duplicate]

The problem is stated as: Let $f$ denote the density function of the random variable $X$. $X$ has a symmetric distribution around $a$, in other words, $f(a+h) = f(a-h)$. Prove that $E(X) = a$, ...
8 views

### Why with glmnet I obtain different coefficients for the different categories I want to classify?

I am performing a multinomial logistic regression using glmnet. I have 7 classes of trees to predict and different predictors. What I do not understand is why when I plot the coefficents vs. log ...
21 views

### How should I calculate mean CI - from raw data or mean values?

I have experimenatal data from medical industry. In the experiment 4 observations were weighted, each one 2 times for more precise measurement. As a final weight, a mean from each pair is reported. ...
24 views

### Defining custom Bayesian priors in R (BayesFactor package)

I'm performing some Bayesian analyses in R using the BayesFactor package, and was wondering whether it is possible to specify priors for the alternative not centered on zero (the current defaults ...
34 views

### Derivation of Formula for linear regression with data points forming a circle

Suppose we have one dimensional data with following conditions.1. The value of this single feature lies in the closed interval [-a,a].2. The associated target value with each data also lies in the ...
16 views

### Just want a quick confirmation on a simple normal distribution problem

Given mean = 167cm, standard deviation is 3cm, a) When four are randomly selected, all of their heights will be greater than 170? b) When four are randomly selected, two will have heights smaller ...
17 views

### Significantly different in categorical variables [on hold]

I am working with a categorical variable with 4 mutually exclusive classifications (CC, CD, DC and DD). I had counted how many times each classification is repeated. (for example, 33 CC, 40 CD, 50 DC ...
8 views

### Three Factor Multiple Comparison Post-Hoc Test for Levene's Test

My research question is to find out whether or not my samples are exhibiting any significant differences in their variance in response to three possible treatments. Here are my possible groups: ...
10 views

### gamboost (mboost) and estimating / controlling random effect variance (brandom learners) [on hold]

I am experimenting with gamboost (package mboost) with the goal of combining a random effects model (random group intercepts) with a boosted tree model. For context, I have already built a standard ...
7 views

### Multivariate Adaptive Regression Splines interpreting hinge coefficients

I am learning MARS using the earth package in R. I read about MARS on page 321 of The Elements of Statistical Learning https://web.stanford.edu/~hastie/Papers/ESLII.pdf and the tutorial here http://...
10 views

### Is expectation maximization an approximation algorithm?

Is expectation maximization an approximation algorithm? Does it give the exact solution?
12 views

### Detect Negative Correlation [on hold]

In the attached image, if I want to detect negative correlation between these two data sets using machine learning algorithms, which one do I choose? I have indicated the boundaries I first need to ...
28 views

### Continous random variable short proof

I am given the problem: If X is a continuous random variable with cumulative distribution function F and density function f, show that the random variable Y = X^2 is also continuous and express its ...
30 views

### How to analyze a small dataset?

I have this dataset and I'm not sure how to analyze it. I threw the classical regression methods such as OLS at it and haven't achieved much success. My response variables are ...
11 views

### Variance inﬂation factors for time series

R code: I got an error by using vif function. ...
21 views

### Why is the convolution of two box kernels a triangle kernel? [duplicate]

Can anyone show the mathematical steps proving $K_{box}*K_{box} = K_{triangle}$
14 views

### summarisng sequences in R? [on hold]

I have a large data set comprising 45,000 days of a rainwater system switching between running on a tank or off the city water mains. The system switches between the two depending on the level in the ...
29 views

### Measuring class imbalance of a dataset [on hold]

Is there a way to measure the balance (i.e. ideal number of positive samples for machine learning) of a dataset? A citation will also be useful.
17 views

### Arima forecasting on dataset with many 0s

I have a dataset which contains 30 0 values out of a total of 80 observations. Is there a good technique to fit an ARIMA model on the data without either removing the 0 values or performing a moving ...
44 views

### Proof of probabilities that may not be independent

I am given the problem: Given $P(A) = \frac{3}{4}$, $P(B) = \frac{3}{8}$, show that: a) $P(A or B) > \frac{3}{4}$. b) $\frac{1}{8} < P(A and B) < \frac{3}{8}$. The problem does not ...
14 views

### How do you derive a risk function from a loss function given a normal distribution? [on hold]

Let X1....X25 be a random sample from a normal distribution N(p,1) such that the domain of p stretches from negative infinity to positive infinity. Let y = X-bar (I.e. the sample mean) Let loss ...
11 views

### Repeated measures ANOVA question

I'm new to statistics and looking for some guidance on choosing my variables for a repeated measures ANOVA. My data set consists of 4 dependent variables: 1. Gait speed 2. Balance test 3. Leg ...
32 views

### How do you select the best from a number of linear models?

I'm learning linear regression with the Carseats data set. I went through the data, cleaned it, encoded the dummy variables and checked for collinearity. The dataset has 400 observations on Carseat ...
35 views

8 views

### A generalized LASSO constraint

I want to use LASSO in R but shrinking towards some fixed vector $A$, instead of shrinking towards 0. The desired L1 constraint, given coefficient vector $\beta$, is $||\beta-A||_{1} \leq k$, rather ...
11 views

### Incorporating uneven sample sizes into linear mixed models

I have run an experiment measuring behaviour of individual animals of different Species. Given that the species are all quite different, I standardised my experiments by biomass, but this means that ...
14 views

### Inverting MA(1) to AR(Inf) [duplicate]

While it is $MA(1)$ process there is no dependence between $u(t)$ and $u(t-1)$ i.e $$u(t)=v(t)+Q(1)v(t-1)$$ but when i converted it to AR process i get $u$’s that is dependent on the other $u$’s i.e. \$...
11 views

### The best (or most conventionally acceptable) way to describe under-representation of a group in a sub-population

Suppose that 50% of the population at large are women, but in a certain field, only 20% of the professionals are women. Suppose further that I want to write a bullet point that reads: ...