# All Questions

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### Testing equality of two X values in quadratic regression

So let's say we have a quadratic relationship between two variables, y and x. Graphically, it is U-shaped. However, there is also a linear component to it, such that the left curve is lower than the ...
72 views

### What is the best way to remember the difference between sensitivity, specificity, precision, accuracy, and recall?

Despite having seen these terms 502847894789 times, I cannot for the life of me remember the difference between sensitivity, specificity, precision, accuracy, and recall. They're pretty simple ...
87 views

### Missing at Random Data in GEE

For a continuous outcome being analyzed using GEE with a linear link, you have assurance that standard errors and point estimates are consistent with a first order trend regardless of distribution of ...
6 views

### Interpretation of interaction term

I have a model: $$\ln({\rm earnings}) = a+b_1{\rm female}+b_2{\rm white}+b_3{\rm female}\times{\rm white}$$ 4{\rm female}4 and 4{\rm white}4 are dummy variables. I have interpreted b_1 and b_2: ...
75 views

### Smoothing spline with dependent coordinates in R

I have a series of patients in whom I have measured the value of a certain blood quantity at several time points. However, the time points vary a lot and the number of measurements range between 2 and ...
50 views

1k views

### Z score transformation for testing group differences in correlations

SPSS Help provides the following help for testing group differences in a correlation, using the GLM approach. See link. It first requires that X and Y are transformed into z scores. Question: When ...
57 views

### GBM Bootstrap Prediction Interval Code Error

based on code presented in thread: How to find a GBM Prediction Interval I am trying to apply this to my dataset. Below is my full code, and I am having issues with the bootstrap function. ...
20 views

### Latent Class Analysis vs. Cluster Analysis - differences in inferences?

What are the differences in inferences that can be made from a latent class analysis (LCA) versus a cluster analysis? Is it correct that a LCA assumes an underlying latent variable that gives rise to ...
13 views

### Naive ElasticNet in the glmnet package

In the R package glmnet, does it calculate the Naive form of ElasticNet or is the output rescaled with the term (1 + lambda)?
28 views

### Name for outer product of gradient approximation of Hessian

Is there a name for approximating the Hessian as the outer product of the gradient with itself? If one is approximating the Hessian of the log-loss, then the outer product of the gradient with itself ...
618 views

### R time-series forecasting with neural network, auto.arima and ets

I've heard a bit about using neural networks to forecast time series. How can I compare, which method for forecasting my time-series (daily retail data) is better: auto.arima(x), ets(x) or ...