Monthly Archives: December 2012

Brief Thoughts on Data Entry: Excel Should Not to Be Used

Over the years I have worked with many people who do the field work to collect data. They have their process and it works for them. However, their work rarely extends beyond data collection. This often means data is collected in Excel. If an observation meets a specific criterion then they are colored yellow, another… Read More »

Category: Uncategorized

Y2K38: Our Own Mayan Calendar…Again

It’s not quite the end of the world as we know it.  We made it through December 21, 2012 unscathed. It’s not going to be the last time we will make it through such a pseudo-calamity.  After all we have built our own end of the world before (e.g. Y2K). Next up January 19, 2038.… Read More »

Category: Uncategorized

True Significance of a T Statistic

The example is more of a statistical exercise that  shows the true significance and the density curve of simulated random normal data.  The code can be changed to generate data using either a different mean and standard deviation or a different distribution altogether. This extends the idea of estimating pi by generating random normal data to determine… Read More »

Category: Uncategorized

Estimating Pi

Recently I’ve been working on some jackknife and bootstrapping problems.  While working on those projects I figured it would be a fun distraction to take the process and estimate pi.  I’m sure this problem has been tackled countless times but I have never bothered to try it using a Monte Carlo approach.  Here is the… Read More »

Category: Uncategorized

Mean Value from Grouped Data

Occasionally, I will get requests from clients to calculate the mean. Most of the time it’s a simple request but from time-to-time the data was originally from grouped data. A common approach is to take the midpoint of each of the groups and just assume that all respondents within that group average out to the midpoint.… Read More »

Category: Uncategorized

Importing Data Into R from Different Sources

I have found that I get data from many different sources.  These sources range from simple .csv files to more complex relational databases, to structure XML or JSON files.  I have compiled the different approaches that one can use to easily access these datasets. Local Column Delimited Files This is probably the most common and… Read More »

Category: Uncategorized

Plotting Likert Scales

Graphs can provide an excellent way to emphasize a point and to quickly and efficiently show important information. Sadly, poor graphs can be a good way to waste space in an article, take up time in a presentation, and waste a lot of ink all while providing little to no information. Excel has made it… Read More »

Category: Uncategorized

Power Analysis and the Probability of Errors

Power analysis is a very useful tool to estimate the statistical power from a study. It effectively allows a researcher to determine the needed sample size in order to obtained the required statistical power. Clients often ask (and rightfully so) what the sample size should be for a proposed project. Sample sizes end up being… Read More »

Category: Uncategorized