Posts

A Study in... Environmental Education

,
Colleges and universities are often looking at their degree programs and course offerings to see what changes may need to be made.  Implementing new courses and programs is a big undertaking for a university and careful consideration must be…
Skewed Distribution Bell Curves

Leaning curves: Skewed distribution

In a previous article, we looked at the standard normal distribution, otherwise known as the “bell” curve.  This time we will describe the non standard distribution pattern known as a skewed distribution.  In the standard normal distribution,…
Paper showing signifcant digits

The Numbers Game: Significant Digits, Rounding and Truncating

It is important for those who work with data to know and understand some of the technical aspects of numbers, both when precise measurements and rounded or estimated figures are involved. In this article, we will look at three related aspects…
average numbers

The Best “Average”? That Depends.

The word “average” in layman terms is what is called the mean in statistics. But the word “average” in statistical terms can refer to any of the three measures of central tendency: mean, median and mode. As a quick review, the mean arithmetic…
Correlation and causation

Not the Same: Correlation and Causation

When the measures of two phenomena (or factors or variables) change in relation to one another, they are said to be correlated. Sometimes, when one phenomenon changes, the other phenomenon changes because of the first one. That is, there is…
Sampling Data

Segmenting Data: Quartiles, Deciles, Percentiles

We often talk about the top 25% or top 10% or even top 1% of something. When we are segmenting data into percentages we commonly are talking about quartiles, deciles and percentiles. Quartiles divide the data into four parts; deciles divide…
Some graphs can report incorrect data findings due to lying with statistics

Not the Whole Truth: Lying with Statistics

Data analysis and the field of statistics are thought to be hard sciences: data is gathered, analyzed using certain processes – often precise mathematical ones – and findings are reported. But this is not always the case. We do not always…
Graph showing Consumer Price Index

Using a “Market Basket”: The Consumer Price Index

Most of us have heard of the Consumer Price Index (CPI), But just what is it and what does it tell us? The CPI is a monthly index produced by the United States Department of Labor’s Bureau of Labor Statistics that “represents changes…
Measures of variability

Measures of Variability

An important aspect of data distribution is the measure of spread (also called variability or dispersion) of the data. These include three measures: range, interquartile range and standard deviation. Range The range of a set of data is a measure…
Eradicating Malaria

Controlling a Killer: Statistics on Eradicating Malaria

,
While malaria is not a very common disease in most developed countries, it still affects millions of people in less-developed countries around the world. Statistics are kept each year by the World Health Organization (WHO) as it and other agencies…