Karl 曹
The Food Export Share Data
I just worked on the food export data of the world and made some visualizations via Excel. Here are the food export share 2020 for...
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KARL'S STUDY BLOG
Karl 曹
Apr 29, 20231 min read
Wage-Price Spirals
Does higher wage necessarily lead to inflation? Here is a presentation for this: Chinese video version： https://www.bilibili.com/video/BV...
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Karl 曹
Apr 17, 20232 min read
Extracting Night Light Data from .tif Files
Thanks for the following blog, which teaches me how to extract nightlight data from .tif file in R: https://berenger.baospace.com/nightli...
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Karl 曹
Mar 20, 20231 min read
Two Sum Problem with ListNode
Intuition The target value for each ListNode equals sum(for i,j in enumerate(list): j*10^i). After adding two values, we can create and...
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Karl 曹
Mar 20, 20231 min read
Indirect Solution for the Roman number to integers
This is a solution for one of the leetcode problems Intuition For each time the combination of IV appears, for example, if we add up I...
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Karl 曹
Feb 26, 20232 min read
Determine the rate of profit in Marxism Economics
In the context of Capital Marx, according to the labor theory of value, the value of a commodity comprises of the value of constant...
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Karl 曹
Jan 17, 20232 min read
Train and Test Data Standardization in Machine Learning
In machine learning, the standardization of data is crucial, because most machine learning algorithms are sensitive to the scale of data....
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Karl 曹
Dec 10, 20221 min read
Note on calculating mean value in R
This is a post about some caveats on calculating mean value in R: 1. If a vector contains NA value, then mean(vector) always returns NA...
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Karl 曹
Nov 23, 20222 min read
Data Visualization Practice for Map
Here are my data visualization works on the rice export data 2020, and the data source is : https://www.fao.org/faostat/en/#data/TCL...
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Karl 曹
Oct 31, 20223 min read
Monte Carlo Simulation for Power Function
As we know, the power of a test is the probability of given H1 being true, and rejecting H0. Usually, we do not know exactly the power of...
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Karl 曹
Oct 17, 20222 min read
Decomposition of MSE, an example of Standard Deviation
Given such a basic setting (a setting that appeared in my Research Module of Econometrics and Statistics): Here sigma_hat is a biased...
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Karl 曹
Oct 15, 20221 min read
How to use Git
Here is my note about how to use git, edited by LaTex This note will be updated with new content sometimes. Find LaTex code from here:...
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Karl 曹
Sep 24, 20224 min read
The Coefficients' Shrinkage Path of Ridge and Lasso Regression
Here we compare the shrinkage path of Ridge and Lasso regression, here the shrinkage path refers to the different coefficients of...
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Karl 曹
Sep 14, 20222 min read
Comparison of PCA, Lasso and Ridge Regression
In this post, I will compare the performance of PCA, Lasso, and Ridge regression at a relatively high dimensional DGP. Number of...
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Karl 曹
Aug 28, 20221 min read
Lasso Implementation in IV Regression
This is my final project for the course Computational Statistics, the file is attached.
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Karl 曹
Aug 16, 20224 min read
Tax is not the revenue of government
Tax is not the revenue of government: Function of Tax in the perspective of Modern Money Theory (MMT) This blog is based on the idea of...
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Karl 曹
Aug 14, 20223 min read
Illustration of Omitted Variable Bias
In this blog, I will show omitted variable bias in an intuitive way. Omitted Variable Bias (OVB) means that in a regression, the...
36 views0 comments
Karl 曹
Jul 22, 20222 min read
The Assumptions for Triple Difference
Triple difference is an extended version of Difference-in-Difference, and it also requires common trend assumption, but according to...
33 views0 comments
Karl 曹
Jul 9, 20224 min read
Story of Institutional Economics ----Moral Hazard
This post is aming to provide a intuitive explanation on the Institutional Economics course, taught by Prof. Dr. Eva Hoppe, University of...
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Karl 曹
Jun 25, 20222 min read
The Directions of Principal Components for PCR/PCA
Principal Component Regression is a regression that uses Principal Components Analysis to select M principal components, and uses these...
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