Jianhong Xu

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Questions related from Jianhong Xu

Why cox regression in survival analysis could be used as prediction model?

From my understanding, the baseline hazard or baseline survival function is unkown because cox regression is semi-parametric model. So why and how can we use it as a prediction model, for example...

29 January 2024 6,910 1 View

How to do descriptive statistics of panel data in Stata?

I have a panel data set and one variable called pain level (which has 4 categories: no, slight, moderate and severe). If I directly write the code of "tab painlevel", Stata will tell me the N...

22 May 2023 7,614 1 View

How to use inverse probability of weighting (IPW) in panel data model?

If I have a panel data survey that collect 100 patients' EQ5D scores by app for their health. One patient can submit their scores more than one times as time passing by. The time in this model is...

06 April 2023 2,551 1 View

How we decide whether a neuron will be activated according to the activation function in the neural network?

I am just wondering that in the neural network if the activation function is Sigmoid function and if we use python to do it. Is the function output value greater than 0.5, the neuron will be...

18 March 2023 7,584 2 View

What is the difference between runing regression sperately or put variables into one regression?

For example, if we want to study the impact of gender on wage. What is the difference if I collect a sample I run a regression and let gender as a dummy variable to compare the impact of gender on...

30 November 2022 4,872 3 View

How to understand the process of Multiple Imputation?

The process of MI is as following: In the first step, the dataset with missing values (i.e. incomplete dataset) is copied several times. Then in the next step, the missing values are replaced...

18 November 2022 9,226 3 View

Can the properties of frequentoist be proved mathematically?

During the lecture, the lecturer mentioned the properties of Frequentist. As following Unbiasedness is only one of the frequentist properties — arguably, the most compelling from a frequentist...

19 October 2022 2,905 4 View

Why does an insignificant regressor become significant if I add some significant control variables?

Currently, I am studying the association between the frequency of extreme temperature and mortality rate. Before I add the Sulfur dioxide emissions as a control variable, the coefficient of my...

27 March 2022 7,619 6 View