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Questions tagged [parametric]

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Is there a statistical test for five groups with averages ONLY?

The data I collected was measuring plant shoot masses and these were extremely small, so I could only find the total mass of the shoots from 30 plants. Hence, I only have the mean and none of the ...
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Why are parametric models usually robust to mild misspecification?

Statisticians often use parametric families of models, for example normal distributions with unknown mean and variance. However, nothing in real life is perfectly normally distributed (or distributed ...
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Parametric copulas with marginals that are regressions

In Dependence Modeling with Copulas (Harry Joe) I'm struggling to interpret the meaning of a statement. In Chaper 5.1, it is stated: Parametric inference for copulas For dependence modeling with ...
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How do I sample new data for a parametric bootstrap with linear regression?

I initially have two data vectors $x$ and $y$, where $y$ is assumed to fit the linear model $y = \beta_0 + \beta_1x + \epsilon$, with $\epsilon \sim N(0,\sigma^2)$. I fit the model using fitlm in ...
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Mapping Parametric Curves with auxiliary variables

The image below displays an approach of using an auxiliary variable to map the parametric curves of a standard normal pdf and cdf. In Equation (1), z as r.v. is clearly one-dimensional. However, after ...
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Comparing before and after survey using Likert Scale

We are trying to measure if there is a difference on the level of interests of participants before and after I let them play a game. The survey is in the form of Likert Scale where ...
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Example of a parametric family of distributions that always has dependence on among its variables

Inspired by this question, I would like an example of a parametric family of distributions such that there is dependence for all choices of parameters. The family could be infinite or finite, but I ...
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How to fit data to a parametric curve/model (x(t), y(t)?

I've got data of x and y pairs and I'd like to fit it to a model that is parametrized as f = (x(t), y(t)). Unfortunately, there is no way for me to analytically solve for t and get a direct ...
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Interpreting AFT Model Coefficients: Mean vs. Median Survival Time in Log-Normal Distribution

When interpreting the coefficients of an Accelerated Failure Time (AFT) model that assumes a log-normal distribution, should we focus on the impact of coefficients on the mean survival time or the ...
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Parametric or non parametric mixed effect models for very small sample size in ecological/soil data?

I am running an ecological/environmental experiment in a salt marsh with 5 experimental treatments and 3 replicate soil samples taken from each treatment. I have been taking measurements from these ...
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Estimators that are superefficient on a dense set

In Chapter 8 of van der Vaart's Asymptotic Statistics, it is shown that (under weak regularity conditions) an estimator can be "superefficient" on at most a set of Lebesgue measure zero (...
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Must an alpha=0.01 be used to interpret significance of parametric terms in a GAM?

I have fit a time-series count HGAM with environmental covariates as parametric terms and year as a site-varying smooth term. I am wondering if I need to use an alpha threshold of 0.01 to interpret ...
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Use of both parametric and non-parametric tests in the same study

Suppose we are investigating whether there is a significant difference in dependent variables A and B between two treatments in a population. Let's assume that the data provide parametric assumptions (...
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Predicting time to event / duration data

I've built a parametric survival model (survreg in R) to predict injury recovery duration using features such as age and treatments. I'm looking at trying model-based boosting using mboost with ...
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What repeated measures statistical tests should I use with uneven sample size and parametrical/nonparametrical distribution?

I'm looking for a way to measure significance + variance homogeneity/heterogenity First of all I tested my data for normality and it's not always parametrical, so I think that I should use different ...
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