Avoiding a Nightmare by Using Math

The answer lies in trigonometry. -Sherlock Holmes

Don't worry if you never learned trigonometry--the answers here lie in arithmetic.

Medical test results often come back positive or negative, as if the result were a certainty. Of course, there is the accuracy, but if the accuracy is 99% or so, what does that really mean? That you should get your affairs in order? Before you call your probate attorney, let's take an example from the book Calculated Risks by Gerd Gigerenzer.

Let's say you're a 40-something year old woman with no symptoms of breast cancer. You have a positive mammogram. What are the odds you have breast cancer?

Using some assumptions about test accuracy and rates of disease based on real data, the odds that you'd have breast cancer are one in eleven according to Gigerenzer. (If you were way off, don't feel bad--most of the physicians Gigerenzer tested were way off, too--and they had the data in front of them. Not that that's comforting in every way.)

A different example: what if you have no risk factors, but have a positive test for HIV? Your odds of actually having HIV are about 50%. But, if the experience of one of Gigerenzer's students who shopped around for good medical advice in Berlin is any indication, you're not likely to hear that from an AIDS counselor. In fact, one counselor--a physician--said, "With certainty, [false positives] do not occur; if there are false results, then only false negatives, occurring when the antibodies have not yet formed." Several of the counselors searched for information on false positives but couldn't find any.

Those with a positive test for a disease have reason to be cautiously optimistic. With a little data and some arithmetic, using a book on probability like Calculated Risks can help you decide how to proceed.

Comments

Generation X Led the Way out of the Pandemic

I keep seeing riled-up Gen Xers on YouTube. You'd better watch out, because Gen X (born between 1965 and 1980) is tough--so tough that some of us looked after ourselves home alone after school, played unsupervised and drank out of hoses when we were kids. The riled-up ones on YouTube might send some very mean tweets. Screen shot from The Goonies. They're late to the party. It was mostly other Gen-Xers who were riled up four years ago, leading the way against lockdowns and forced vaccinations: Alex Berenson (investigative journalist who successfully sued Twitter), Bret Weinstein and Heather Heying ( professors in exile previously pursued by baseball bat wielding goons at Evergreen), Jay Bhattacharya and Sunetra Gupta (co-authors of The Great Barrington Declaration ), Aseem Malhotra (cardiologist who took the shot, then started campaigning to end the shots after his father died suddenly of a heart attack after his shot), Ron De Santis and Kristi Noem (governors of Florida and

How to block a member on the Inner Circle Forum

If you're a member of Dr. Davis's Inner Circle site and you use the forum, you can block a member so you don't see most of their posts, but the process isn't very intuitive. Here's how. Thread on blocking a member: https://innercircle.drdavisinfinitehealth.com/forum/topics.aspx?ID=3092

Mild Fermented Pickles Recipe

If you don't like fermented foods because they're too tart or sour, you might like these pickles. There's no vinegar or sharp taste. Even the onions are mild. They're not sweet, either, even though the recipe calls for brown sugar: the bacteria consume most or all of the sugar. They're just mild, savory pickles. There's no need to add culture because cucumbers naturally have L. plantarum bacteria on their surface. Equipment needed 1 quart canning jar* with ring and lid (or fermenting lid) 1 fermentation weight or small, clean stones in a Ziploc baggie Ingredients 1 pound pickling cucumbers** (not salad cucumbers), preferably unwashed 1/4 sweet onion (like Vidalia) 1 teaspoon juniper berries 1 teaspoon turmeric 1 teaspoon whole black peppercorns 1/2 teaspoon anise seed 1 tablespoon brown sugar 3 tablespoons pickling salt or other salt without iodine 1/4 teaspoon pickle crisp Filtered water free of chlorine Instructions Rinse the cucumbers in the filtered water

Carrageenan: A Sickening Thickener. Is it a Migraine Menace?

Let me tell you about my ride in an ambulance last night. I woke up at six o'clock from a nap with a mild headache. I ate dinner and took my vitamins, along with a couple of extra magnesium pills. Since magnesium helps my TMJ flare-ups, I thought it might help my headache. Then I went to see my mother. A few hours later, I had a severe headache, sinus pain and nausea. During a brief respite from the pain, I left for home, but less than a mile later, I got out of my car and threw up. A cop, Officer Fisher, pulled up behind me and asked if I was okay. He believed me when he said I hadn't been drinking, but he said I seemed lethargic and he wanted the paramedics to see me. (Later he mentioned that a man he'd recently stopped was having a stroke.) Thinking I had a migraine headache, the paramedics wanted to take me to the hospital. But since I knew that doctors don't know what causes migraine headaches, and I didn't know what effect their medicine would have on m

Atkins on Salad

"...you're allowed green salad with your lunch and dinner. Yes, even though this first week of the diet is called a carbohydrate-free diet and lettuce contains a tiny bit of carbohydrate....Given the amount of carbohydrate in these two salads, what happens in the body is approximately the same in 99 percent of dieters as if no salad had been eaten. So why not eat those salads? They are a lifesaver. To eat just protein and fat without the garden-fresh crispness that salad provides is a drudgery. So I thank the Lord that greens contain so little carbohydrate. Those salads make all the difference between a diet that's aesthetic, appetizing, human, and one that's an uncivilized drag." --Dr. Robert Atkins(1) Dr. Atkins also said, "A patient christened the [Atkins Diet] the steak and salad diet--and that does rather sum up the plot of it."(2) So much for low carb diets in general and Atkins in particular being all-meat diets. Most people I see commenting onlin

Pain, Pain, Go Away!

Search This Blog