A Fine Slice Of SQL Server
A common undertaking in applied research settings such as in some areas of psychology is to convert a raw score into some type of standardized score such as z-scores.
This post shows a way how to accomplish that.
Read on for three techniques.
Comments closedMichael Toth explains some of the functionality available in base R (that is, not packages like lubridate) for working with dates:
When working with R date formats, you’re generally going to be trying to accomplish one of two different but related goals:
1. Converting a character string like “
Jan 30 1989” to a Date type2. Getting an R Date object to print in a specific format for a graph or other output
You may need to handle both of these goals in the same analysis, but it’s best to think of them as two separate exercises. Knowing which goal you are trying to accomplish is important because you will need to use different functions to accomplish each of these. Let’s tackle them one at a time.
There are some good insights in the post. H/T R-bloggers
Comments closedJohn Mount gives us a directed graph of popular R packages:
In the above diagram each node is an R package. We are restricting our selves to popular extension packages: those that have at least 1,000 indirect uses in CRAN (via Depends/Imports/LinkingTo; excluding base packages such as stats and utils).
John has some interesting insights here as well.
Comments closedSebastian Sauer works out a coin flip problem:
A stochastic problem, with application to financial theory. Some say it goes back to Warren Buffett. I relied to my colleague Norman Markgraf, who pointed it out to me.
Assume there are two coins. One is fair, one is loaded. The loaded coin has a bias of 60-40. Now, the question is: How many coin flips do you need to be “sure enough” (say, 95%) that you found the loaded coin?
Let’s simulate la chose.
It took a few more flips than I had expected but the number is not outlandish.
Comments closedJohn Mount explains Standard Evaluation versus Non-Standard Evaluation in R:
In standard (or value oriented evaluation) code you type in is taken to be variable names, functions, names, operators, and even numeric literal values. String values or literals need extra marks, such as quotes.
John walks us through several examples along the way. At the end, John is a major proponent of Standard Evaluation over Non-Standard Evaluation.
Comments closedBack in August of 2017, we wrote two posts #9: Compating your Share Libraries and #10: Compacting your Shared Libraries, After The Buildabout “stripping” shared libraries. This involves removing auxiliary information (such as debug symbols and more) from the shared libraries which can greatly reduce the installed size (on suitable platforms – it mostly matters where I work, i.e. on Linux).
There’s a pretty good space savings in the tidyverse package. H/T R-Bloggers.
Abhijit Telang shares a few techniques for doing post-regression residual analysis using R:
Naturally, I would expect my model to be unbiased, at least in intention, and hence any leftovers on either side of the regression line that did not make it on the line are expected to be random, i.e. without any particular pattern.
That is, I expect my residual error distributions to follow a bland, normal distribution.
In R, you can do this elegantly with just two lines of code.
1. Plot a histogram of residuals
2. Add a Quantile-Quantile plot with a line that passes through, namely, the first and third quantiles.
There are several more techniques in here to analyze residuals, so check it out.
Comments closedLaura Ellis takes us through ggplotly:
As someone very interested in storytelling, ggplot2 is easily my data visualization tool of choice. It is like the Swiss army knife for data visualization. One of my favorite features is the ability to pack a graph chock-full of dimensions. This ability is incredibly handy during the data exploration phases. However, sometimes I find myself wanting to look at trends without all the noise. Specifically, I often want to look at very dense scatterplots for outliers. Ggplot2 is great at this, but when we’ve isolated the points we want to understand, we can’t easily examine all possible dimensions right in the static charts.
Enter plotly. The plotly package and ggploty function do an excellent job at taking our high quality ggplot2 graphs and making them interactive.
Read on for several quality, interactive visuals.
Comments closedJohn Mount covers a change in tidyr which mimics Mount and Nina Zumel’s pivot_to_rowrecs and unpivot_to_blocks functions in the cdata package:
If you want to work in the above way we suggest giving our
cdatapackage a try. We named the functionspivot_to_rowrecsandunpivot_to_blocks. The idea was: by emphasizing the record structure one might eventually internalize what the transforms are doing. On the way to that we have a lot of documentation and tutorials.
This is your regular reminder that the Tidyverse is very useful, but it is not the entirety of R.
Comments closedJohn Mount makes the point that packages dependencies are innately a risk:
If your software or research depends on many complex and changing packages, you have no way to establish your work is correct. This is because to establish the correctness of your work, you would need to also establish the correctness of all of the dependencies. This is worse than having non-reproducible research, as your work may have in fact been wrong even the first time.
Low dependencies and low complexity dependencies can also be wrong, but in this case there at least exists the possibility of checking things or running down and fixing issues.
There are some insightful comments on this post as well, so check those out. This is definitely an area where there are trade-offs, so trying to reason through when to move in which direction is important.
Comments closed