KeepNotes blog

Missing data is inevitable for several reasons during the clinical trials. As we know, missing data can be classified into one of three categories, like MCAR(Missing Completely At Random), MAR(Missing At Random) and MNAR(Missing Not At Random).

As indicated in the title, this article will discuss how to solve this problem in ggplot2.

OpenAI于3月1日发布了ChatGPT API，但其只提供了Python中如何调用此API的文档说明。尽管没提到如何使用R来调用，但是毫无疑问R肯定是可以的，所以我用google搜了下。以下是基于网上资料而整理的简短介绍，如何在R中用ChatGPT。

Here is just a trick note to demonstrate how to split the column when you use the mutate function from the dplyr package in R.

Survival analysis is often used in tumor clinical trials, and there are usually two estimations that appear in the report: the median survival time and the median follow-up time.

Partial dates are very common in clinical trials, such as AE that allow some parts of the date or time to be missing. However, when you create the ADaM dataset for AE, some variables like ASTDT (Analysis Start Date) or AENDT (Analysis End Date) are numeric, so they can be derived only when the date is complete and then you can calculate the durations.

I'm a R-lover and believe that anything SAS can do, R can do better. As R is such a powerful language for statistical analysis in clinical trials. Once, I posted an article that said how to insert blank rows, so I looked up how to do that in R.

This casual note is to record how to use R to replace the NA with 0 or any string. Generally, NA can be generated for different reasons, like unclean data, data transformation, or missing values. Otherwise, we have to convert NA to zero or other stings in order to present them in tables or listings.

The box plot is used to demonstrate the data distribution in common and to look for outliers. We can also see where the 25% and 75% quarters are, as well as the median value from the box. As a result, it's a very helpful visual chart.

Recently, I'm a little confused how to create or save PNG graphs in SAS. Normally, we would have been to create RTF or PDF instead but there was sometimes a specific requestment to save as PNG directly. So we need to know how to complete it in SAS when I have a graph generated by SGPLOT or GTL procedure.

This article aims to learn the basic calculation process of least-squares means (LS means).

This article is to illustate how to conduct an (Analysis of Covariance) ANCOVA model to determine whether or not the change from baseline glucose is affected by treatment significantly. In other words, using ANCOVA to compare the adjusted means of two or more independent groups while acounting for one or more covariates.

As a new SAS user, a common question that is always asked and searched on google is: how can I get the statistic into a table?

This post is just a note referred from one article as shown below that I think would be beneficial for anyone who is as new as I am, as this requirement is fairly common in pharamaceutical programming.

一些过往学习的记录，均是参考和摘抄了一些网上的资料，无法保证描述的准确性。。。

http://onbiostatistics.blogspot.com/2009/01/data-dredging-vs-data-mining-post-hoc.html

这个是当初最开始学习用SAS的时候做的笔记，现在再次看到有点亲切和熟悉，初学者看书做笔记的感觉。。。

回过头看，这些非常基础的用法却是平时用的最多的代码。

If you'd like to add one blank row in your report, as shown below:

Here is to present a set of SDTM and ADaM datasets from CDISC pilot projects as resources for R develpment and programming.

In this article, we are going to present how to work with files and folders in R and SAS.

The Bland-Altman analysis is the most common method of assessing the agreement in method comparison in IVD CT or CE trials.