From Volume 5, Issue 3, July 2012 | Pages 82-88
There is an increasing volume of research undertaken within orthodontics and with this comes a need to evaluate what is available. This short series aims to help the orthodontist revise basic concepts of critical appraisal and pertinent statistics.
Information is collected for specified variables to provide the data to address a chosen research question. They are called variables as they provide information as to how individuals or items vary. The appropriate summary measures and statistics to use depend on how the variable is classified.
Classification is within one of several categories. If there are only two categories (for example, male or female) then the variable is known as binary or dichotomous. If there are more than two categories, then these may be either ordered (for example, low, average and high angle) so the variable is known as ordinal, or unordered, with the categories bearing no mathematical relationship to each other (for example, country of birth or ethnicity) when the variable is known as nominal. The number in each category may be expressed as proportions or percentages of the total, or as the risk or the odds of being in one category relative to another. A contingency table is often used to summarize the data.
Thank you for visiting Orthodontic Update and reading some of our resources. To read more, please register today. You’ll enjoy the following great benefits:
What's included
