Ou Zhang https://ouzhang.me/ Recent content on Ou Zhang Hugo -- gohugo.io en Tue, 05 Apr 2022 00:00:00 +0000 RStudio Conference 2019 Notes at Austin https://ouzhang.me/resource/rstudio_conf2019/ Fri, 18 Jan 2019 00:00:00 +0000 https://ouzhang.me/resource/rstudio_conf2019/ A RStudio Conference 2019 Notes at Austin Quotient ADHD Diagnosis System https://ouzhang.me/project/quotient/ Fri, 20 Oct 2017 00:00:00 +0000 https://ouzhang.me/project/quotient/ Quotient ADHD Diagnosis System General Intelligence G-loading https://ouzhang.me/project/g-loading/ Fri, 10 Apr 2015 00:00:00 +0000 https://ouzhang.me/project/g-loading/ General Intelligence G-loading Outlier Detection https://ouzhang.me/resource/outlier/ Thu, 19 Nov 2020 00:00:00 +0000 https://ouzhang.me/resource/outlier/ Outlier Detection tutorial and codes Parallel Analysis https://ouzhang.me/resource/parallel_analysis/ Mon, 13 Apr 2020 00:00:00 +0000 https://ouzhang.me/resource/parallel_analysis/ Parallel Analysis tutorial and codes Logistic Regression and ROC in SAS https://ouzhang.me/resource/logit_sas/ Wed, 20 Nov 2013 00:00:00 +0000 https://ouzhang.me/resource/logit_sas/ Logistic Regression and ROC in SAS My Useful SAS Resources https://ouzhang.me/blog/sas-tips/ Tue, 05 Apr 2022 00:00:00 +0000 https://ouzhang.me/blog/sas-tips/ Story Key Programming Talk Key notes Repo structure Other source on the internet Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/2022-04-05-sas -tricks/index.html Here is my R Markdown source file: blog/2022-04-05-sas -tricks/index.Rmd You'll want to edit this file, then re-knit to see the changes take effect in your site preview. To remove me, delete this line inside that file: {{< here >}} The Evolution Story of My Website https://ouzhang.me/blog/blogdown/ Tue, 01 Mar 2022 00:00:00 +0000 https://ouzhang.me/blog/blogdown/ This blog intends to display my website evolving path. Meanwhile, it also provides a roadmap for those who want to build website for yourself. 9 Join Function Example with the R {dplyr} Package https://ouzhang.me/blog/nine-join/ Wed, 25 Nov 2020 00:00:00 +0000 https://ouzhang.me/blog/nine-join/ Simple Example Data Load {dplyr} package Function 1: inner_join Function 2: left_join Function 3: right_join Function 4: full_join Function 5: semi_join Function 6: anti_join Complex Example 1: Join Multiple Data Frames Complex example 2: Join by Multiple Columns Complex example 3: Join Data & Delete ID Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/2020-11-25-nine-join/index.html Here is my R Markdown source file: blog/2020-11-25-nine-join/index. Outliers-Part 4:Finding Outliers in a multivariated way https://ouzhang.me/blog/outlier-series/outliers-part4/ Mon, 16 Nov 2020 00:00:00 +0000 https://ouzhang.me/blog/outlier-series/outliers-part4/ Data Source Variables in Data Model-specific methods Cook’s Distance Pareto Multivariate methods Mahalanobis Distance Details about Mahalanobis Distance Robust Mahalanobis Distance Minimum Covariance Determinant (MCD) robust tolerance ellipsoid (RTE) Invariant Coordinate Selection (ICS) OPTICS Isolation Forest Local Outlier Factor ‘check_outliers’ function in {performance} R package Threshold specification Reference Hi, I'm the here-bot cat! Use me to find your way in your website. Outliers-Part 3:Outliers in Regression https://ouzhang.me/blog/outlier-series/outliers-part3/ Mon, 09 Nov 2020 00:00:00 +0000 https://ouzhang.me/blog/outlier-series/outliers-part3/ Types of Unusual Observations Regression Outliers Leverage Influential Observations Good vs. Bad Leverage Detecting Influential Observations Graphic diagnostics A scatter plot with Confidence Ellipse Quantile Comparison Plots (QQ-Plot) Rule of Thumb Added-variable plots Numerical diagnostics Hat Matrix Rule of Thumb Standardized Residuals Rule of Thumb Studentized Residuals Rule of Thumb Studentized Residuals-the Bonferroni adjustment DFBeta and DFBetas Rule of thumb Robust Distance Mahalanobis Distance Rule of Thumb Cook’s Distance Rule of Thumb DFITS Rule of Thumb Summary Hi, I'm the here-bot cat! Outliers-Part 2:Finding Outliers in a univariated way https://ouzhang.me/blog/outlier-series/outliers-part2/ Tue, 03 Nov 2020 00:00:00 +0000 https://ouzhang.me/blog/outlier-series/outliers-part2/ Method 1: Sorting Your Datasheet to Find Outliers Method 2: Graphing Your Data to Identify Outliers Histogram Boxplot Adjusted boxplot (Hubert and Vandervieren, 2008) Method 3: Using Z-scores to Detect Outliers Z-Score pros: Z-Score cons: Method 4: Using the Interquartile Range (IRQ) to Create Outlier Fences Method 5: Percentiles scores function from {outliers} packages Method 6: Hampel filter Method 7: Finding Outliers with Hypothesis Tests Grubbs’ test Dixon’s test Rosner’s test Challenges of Using Outlier Hypothesis Tests: Masking and Swamping Hi, I'm the here-bot cat! Outliers-Part 1:Causes, Philosophy and General Rules https://ouzhang.me/blog/outlier-series/outliers-part1/ Mon, 02 Nov 2020 00:00:00 +0000 https://ouzhang.me/blog/outlier-series/outliers-part1/ What are Outliers? Causes for Outliers Types of Outliers Philosophy about Finding Outliers General Rules Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/outlier-series/01-Outliers-part1/index.html Here is my R Markdown source file: blog/outlier-series/01-Outliers-part1/index.Rmd You'll want to edit this file, then re-knit to see the changes take effect in your site preview. To remove me, delete this line inside that file: {{< here >}} Introducing Tidyverse-Part 2: %>%, the Forward Chaining https://ouzhang.me/blog/2020-05-22-pipe-forward-chaining/ Fri, 22 May 2020 00:00:00 +0000 https://ouzhang.me/blog/2020-05-22-pipe-forward-chaining/ Figure 1: Pipe Operator Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/2020-05-22-pipe-forward-chaining/index.html Here is my R Markdown source file: blog/2020-05-22-pipe-forward-chaining/index.Rmd You'll want to edit this file, then re-knit to see the changes take effect in your site preview. To remove me, delete this line inside that file: {{< here >}} My content section is: blog My layout is: single-sidebar Images in this page bundle: /blog/2020-05-22-pipe-forward-chaining/featured. Introducing Tidyverse-Part 1:Tidy Data https://ouzhang.me/blog/tidy-data/ Sat, 09 May 2020 00:00:00 +0000 https://ouzhang.me/blog/tidy-data/ What is Tidy data？ Why is it important? Fixed variable vs. Measured variable Is such a data set tidy? Example 1: Example 2: Example 3: Code Examples Traditional measurement testing dataset Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/2020-05-09-tidy-data/index.html Here is my R Markdown source file: blog/2020-05-09-tidy-data/index.Rmd You'll want to edit this file, then re-knit to see the changes take effect in your site preview. Comparing norming methods performance under violation of the assumptions https://ouzhang.me/publication/2020-ncme-norm/ Thu, 23 Apr 2020 00:00:00 +0000 https://ouzhang.me/publication/2020-ncme-norm/ Impacts of human communication network topology on group optimism bias in Capital Project Planning: a human-subject experiment https://ouzhang.me/publication/2019-human-network/ Thu, 23 Apr 2020 00:00:00 +0000 https://ouzhang.me/publication/2019-human-network/ Parallel Analysis: Determining the Dimensionality of Data https://ouzhang.me/blog/parallel-analysis-determining-the-dimensionality-of-data/ Mon, 13 Apr 2020 00:00:00 +0000 https://ouzhang.me/blog/parallel-analysis-determining-the-dimensionality-of-data/ window.xaringanExtraClipboard(null, {"button":" Copy Code","success":" Copied!","error":"Press Ctrl+C to Copy"}) WHAT IS PARALLEL ANALYSIS METHODOLOGY PARALLEL ANALYSIS IN R Recently, my colleague asked me to review a state assessment tech report. In the tech report, a section-“Parallel Analysis” really caught my eyes. I have done parallel analysis multiple times in the past. However, I have never thought about this topic in a systematical way. It is always a good memory refreshing opportunity. Fight with TinyTex and Rmarkdown can't knit to PDF on my PC https://ouzhang.me/blog/fight-with-tinytex-and-rmarkdown-can-t-knit-to-pdf-on-my-pc/ Sun, 23 Feb 2020 00:00:00 +0000 https://ouzhang.me/blog/fight-with-tinytex-and-rmarkdown-can-t-knit-to-pdf-on-my-pc/ Hi, I'm the here-bot cat! Use me to find your way in your website. Here I am: content/blog/2020-02-23-fight-with-tinytex-and-rmarkdown-can-t-knit-to-pdf-on-my-pc/index.html Here is my R Markdown source file: blog/2020-02-23-fight-with-tinytex-and-rmarkdown-can-t-knit-to-pdf-on-my-pc/index.Rmd You'll want to edit this file, then re-knit to see the changes take effect in your site preview. To remove me, delete this line inside that file: {{< here >}} My content section is: blog My layout is: single-sidebar Images in this page bundle: /blog/fight-with-tinytex-and-rmarkdown-can-t-knit-to-pdf-on-my-pc/featured. Soccer Game https://ouzhang.me/blog/soccer-game/ Sun, 16 Feb 2020 00:00:00 +0000 https://ouzhang.me/blog/soccer-game/ San Antonio Sunday Soccer League Game with my son First blog and some words https://ouzhang.me/blog/first-blog-and-some-words/ Fri, 14 Feb 2020 00:00:00 +0000 https://ouzhang.me/blog/first-blog-and-some-words/ Yihui Xie Keith McNulty David Robinson Useful links This is the first blog I created after I put my personal website online. This is the second time I’ve built my personal website. Last time, when I built my first one, I was still in graduate school fighting for my dissertation. It seems like a Déjà vu, but two websites serve as two different purposes. My first website was mainly used for advertising and job hunting. VBA and DDE automated way to populate table into formatted Excel https://ouzhang.me/talk/2019-dde-vba/ Mon, 15 Apr 2019 14:00:01 -0700 https://ouzhang.me/talk/2019-dde-vba/ VBA + DDE: automated way to populate table into formatted Excel Contact https://ouzhang.me/contact/ Mon, 25 Feb 2019 13:38:41 -0600 https://ouzhang.me/contact/ ** Contact page don’t contain a body, just the front matter above. See form.html in the layouts folder. Formspree requires a (free) account and new form to be set up. The link is made on the final published url in the field: Restrict to Domain. It is possible to register up to 2 emails free and you can select which one you want the forms to go to within Formspree in the Settings tab. Write Readable Code https://ouzhang.me/talk/2018-readable_code/ Sun, 22 Jul 2018 14:00:01 -0700 https://ouzhang.me/talk/2018-readable_code/ Write readable code: Simple and Practical Techniques for Better Statistical Programming. How much can we gain from collateral information for subscore reporting? https://ouzhang.me/publication/2017-ncme-subscore/ Mon, 17 Apr 2017 00:00:00 +0000 https://ouzhang.me/publication/2017-ncme-subscore/ Factor invariance between genders on the Wechsler Intelligence Scale for Children–Fifth Edition https://ouzhang.me/publication/2015-mi-wisc5/ Sun, 15 Nov 2015 00:00:00 +0000 https://ouzhang.me/publication/2015-mi-wisc5/ Cross-Cultural Measurement Equivalence of the WISC5 https://ouzhang.me/publication/2015-apa-mi-wisc5/ Fri, 17 Jul 2015 00:00:00 +0000 https://ouzhang.me/publication/2015-apa-mi-wisc5/ A comparison of clinical classification accuracy using CDM and MIRT https://ouzhang.me/publication/2015-ncme-cdm/ Sat, 18 Apr 2015 00:00:00 +0000 https://ouzhang.me/publication/2015-ncme-cdm/ Measurement Invariance-A Theoretical Framework in CFA https://ouzhang.me/talk/2014-measurement_invariance/ Sun, 21 Sep 2014 14:00:01 -0700 https://ouzhang.me/talk/2014-measurement_invariance/ A brief introduction of the measurement invariance theory framework Item Pool Design for Constrained CAT with Non-standard Normal Distributions https://ouzhang.me/publication/2014-ncme-cat/ Sun, 18 May 2014 00:00:00 +0000 https://ouzhang.me/publication/2014-ncme-cat/ Performance Comparisons Between Parametric and Nonparametric DIF Methods https://ouzhang.me/publication/2014-aera-dif/ Sat, 17 May 2014 00:00:00 +0000 https://ouzhang.me/publication/2014-aera-dif/ A Comparison of Parameter Recovery Using different Computer Programs and R-Packages in Estimating the Graded Response Model https://ouzhang.me/publication/2014-aera-irt/ Mon, 12 May 2014 00:00:00 +0000 https://ouzhang.me/publication/2014-aera-irt/ WPPSI-IV Interpretive Assistant 1.0 Interpretive software accompanying S. E. Raiford & D. L. Coalson https://ouzhang.me/publication/2014-wppsi-book/ Mon, 17 Mar 2014 00:00:00 +0000 https://ouzhang.me/publication/2014-wppsi-book/ Observed Score and True Score Equating for Multidimensional Item Response Theory under Nonequivalent Anchor Test Design https://ouzhang.me/publication/2013-ncme-mirt/ Thu, 18 Apr 2013 00:00:00 +0000 https://ouzhang.me/publication/2013-ncme-mirt/ Multi-dimensional Item Response Theory https://ouzhang.me/talk/2012-mirt/ Wed, 03 Oct 2012 14:00:01 -0700 https://ouzhang.me/talk/2012-mirt/ A brief introduction of the Multi-dimensional Item Response Theory R & RStudio Introduction https://ouzhang.me/talk/2012-r_intro/ Tue, 02 Oct 2012 14:00:01 -0700 https://ouzhang.me/talk/2012-r_intro/ A brief introduction of the R and RStudio Detecting Differential Item Functioning in Polytomously Scored Items: A Multilevel Approach to the Generalized MantelHaenszel https://ouzhang.me/publication/2011-ncme-dif/ Sun, 24 Apr 2011 00:00:00 +0000 https://ouzhang.me/publication/2011-ncme-dif/ How Subgroup Characteristics Effect Equating Methods’ Academic Growth Detection? https://ouzhang.me/publication/2011-ncme-subgroup/ Sat, 23 Apr 2011 00:00:00 +0000 https://ouzhang.me/publication/2011-ncme-subgroup/ A Model Evaluation When Association Exists Between Testlets under Small Testlet Size Situations https://ouzhang.me/publication/2011-ncme-testlet/ Fri, 22 Apr 2011 00:00:00 +0000 https://ouzhang.me/publication/2011-ncme-testlet/ Contributors https://ouzhang.me/contributors/ Mon, 01 Jan 0001 00:00:00 +0000 https://ouzhang.me/contributors/ Thank you to all the folks who have contributed both technical and creative skills to this project: Desirée De Leon 🦒 (designed 5 of the custom color themes, made illustrations for the workshop, and provided general aesthetic feedback along the way) Garrick Aden-Buie 🧙‍♀️ (debugged headroom.js and lent his panelset.js code to the theme) Allison Horst 🐕 (awesome illustrations of campfires, seedlings, and evergreens, as well as my R Markdown hedgehog mascot 🦔) License https://ouzhang.me/license/ Mon, 01 Jan 0001 00:00:00 +0000 https://ouzhang.me/license/ My blog posts are released under a Creative Commons Attribution-ShareAlike 4.0 International License.