By: Alanna Rohan (Original Post Here)
Let me be real with you: I don’t like numbers. In fact, many of my math classes during my educational career were spent zoning out and daydreaming instead of multiplying and dividing. But the reality is, numbers are a part of life…from making purchases to telling time. And one division of math that I believe is particularly relevant in everyday life but is not discussed enough, especially in the world of health, is statistics.
Why should I care about health statistics?
We encounter health choices all of the time that make it necessary to understand basic probabilities and their connection to our lives.
Give me an example.
According to Gigerenzer et al. (2008), in 1995, the U.K. Committee on Safety and Medicine sent a warning to doctors, pharmacists, and other health professionals about the dangers of third-generation birth control pills, claiming that the risk of getting a blood clot as a result of taking the pill was 100 percent greater.
The problem with this warning, however, is that this percentage referenced is a relative risk and not an absolute risk.
An absolute risk states the issue in terms the human mind can easily understand.
For example, a hypothetical absolute risk in this scenario would be that the birth control pill increases the chances of getting a blood clot from 1 person in 7,000 to 2 people in 7,000. If you read that you wouldn’t panic, right? That’s just the difference of one person.
Stated as a relative risk, however, this change is 100% (jumping from one person to two people is a 100% increase). But that percentage doesn’t give you a clear picture of the numbers that were used to calculate the percentage, does it? Hearing that your chances of getting a blood clot are 100% greater if you take birth control would really give you pause when considering that choice. Which is exactly what happened in 1995, as there was an estimated 13,000 additional abortions AND an additional birth for every abortion that year after the warning was released (Gigerenzer et al., 2008).
Are there any other confusing statistics out there?
Sure there are! Gigerenzer et al. (2008) describe survival rate vs. mortality rate as another confusing statistical concept, and cite a statement made by Rudy Giuliani as an example. Rudy Giuliani stated in a campaign ad that he was lucky to have had prostate cancer in the U.S., as the prostate cancer survival rate was much higher in the United States than in England (82% vs. 44%). However, these statistics are skewed as they are based on survival rate calculations (a ratio of the number of diagnosed individuals alive 5 years post-diagnosis to the number of people who were diagnosed) and not mortality rates (a ratio of the number of people who died from a particular illness during a one year period to the total number of people in a population). In simpler terms, more people may have survived from prostate cancer in the U.S., but also more people likely died due to the U.S. having a larger population than in England. While survival rate sounds like an important statistic to consider in health discussions, it is ultimately less telling due to factors such as overdiagnosis and lead-time bias.
I know - it all makes you scratch your head a bit. Instead of continuing to potentially bore you with the details, I’ve noted some of the more important ideas to take away below.
Okay, I don’t have the time or money for a statistics degree. What do I do?
A lot of information we receive about health, including health statistics, comes in an isolated form. So, it’s crucial to do some sleuthing. Try your best to always consider the following in regards to health research and statistics:
1. Know that there are many ways to present health statistics – Health statistics can be presented in several ways, and some companies may present the statistics strategically in order to exaggerate or reduce the risks related to a health issue or action.
Also, many health articles and speeches are written by journalists or politicians who have no medical background or training that would enable them to read and interpret health statistics. Unfortunately even many doctors struggle with knowing the right health statistics!
2. Compare your stats to other stats so you can understand them better – Put the stats in perspective to rationalize your concerns. For example, the likelihood of a woman getting breast cancer might be higher than that of a man, but if you are a healthy woman in your twenties, the likelihood of it happening to you anytime soon is still very slim.
3. Does this information really apply to ME? All research is performed on a limited group of people. Do your research on the research to find out more about the particular limitations the study presents, as journalists often leave out this information to make the results seem more drastic than they really are.
4. Don’t just make decisions based on the personal stories of others – When we get sick, we usually turn to people we know for advice and answers. While it can be helpful to hear the suggestions of others, one person's experience may not give you a good sense of how to move forward with a health issue of your own.
Despite easily aiding and abetting hypochondriacs with websites like WebMD, one good thing about the internet is it also gives us access to information about the big picture on health. We can go to websites find reliable statistics and information from medical professionals that aren't skewed by journalism. However...
Things to Keep in Mind While Looking for Health Information Online:
What Questions Could I Ask My Doctor?
The bottom line: Be inquisitive! Ask questions when you meet with a healthcare professional. Look beyond the statistics presented and find the information that will make the statistics make sense to you.
Gigerenzer, G., Gaissmaier, W., Kurz-Milcke, E., Schwartz, L.M., Woloshin, S. (2008). Helping doctors and patients make sense of health statistics. Association for Psychological Science, 8 (2), 53-96.