Okay, welcome. My name is Devine. This is episode 458 of the Devine Intervention

podcast. In this podcast I'm going to be talking about biases associated with screening tests.

This is actually a kind of a high topic many people really struggle with it.

But again I will try to clarify this here. So there are three major biases we see with screening tests on USMLA exams.

Selection bias is one, late time bias is the other,

length time bias is another one.

So let's go through them.

You know, the simple one, actually,

none of them are exactly easy to understand,

but if you really follow what I'm explaining, you'll get the stuff down. So first one is screening bias. The thing is, think about it. The people that get screened for diseases, they're generally people that, I mean think about if you're going like,

oh doctor please I need my bamogram at 40 da da da da da da. People that actively seek out

their own screening chances are they have have higher socioeconomic status, they probably have higher

levels of education, they're probably wealthier, those are just put that pay more attention to their

health, versus suppressing that doesn't really seek out screen

and has to be reminded all the time. That person is probably at a lower socioeconomic status, probably

like not as wealthy, probably doesn't really pay much attention to their health. So you can already see that the

person that gets screening, it's probably a person that is able to get access to better medical care, better physicians

and whatnot. So those people probably do better health-wise. So you can then see, oh wow, this screening test really improves survival.

But it just so happens that the population you're screening is just a population that gets better health care or has better health care

habits than a population you're not screening.

So selection bias is something that can certainly happen with screening tests. Now the second kind of one I want to discuss is lead time bias, right?

So lead time bias, pretty, really lead and length time bias. They are biases where you overestimate the survival. You pretty much overestimate the

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