![]() Check the definition of specificity and you can see how reducing the number of false positives can lead to higher specificity (hopefully). Thus we have reduced our false positives. We then further refine those positive results by testing again and some of the test one positive results will now show up accurately as test two negatives. So in a way, we know in our first pool of positive test results that we have some number of false positives. Keep in mind that a subject has to test positive in both tests in order to be counted as disease positive. By doing so, you have reduced the number of false positives because you are checking one group of positive results with another test. Sequential testing results in higher specificity because you are taking the positive test results and retesting them. Assume the standard positive test means having the disease and whatnot. So I will try my best on mobile, to save some finger cramping, I will assume you know the textbook definitions to all of the terms you stated. I'm not sure is be much help with your other questions though, sorry. ![]() (If you test positive, there is a50/50 chance you're TRULY infected).Ĭan you see the relationship between the disease prevalence and my ability to evaluate the value (certainty) of a positive result? This is my positive predictive value. Now if I tested the same size group of people (200), but this group has an HIV infection prevalence of 1%, I would now expect to see 2 TRUE positive results (along with my 2 FALSE positive results) can I predict the value of a positive test result in this case? In this case, my positive predictive value is 50%. Can I predict how many of those positives are truly infected? So, now let's imagine that it is exactly 99% specific, and for every 100 healthy people I test, I get exactly one false positive. Because it's 100% sensitive, it always detects all HIV cases, but since it's only 99% specific, it sometimes (very rarely) is reactive when HIV is not present. So, I create a lab test that is 100% sensitive to HIV, but only 99% specific. See our wiki for our enforcement and appeals processes. Career and education advice posts are only permitted on Tuesday (GMT). ![]() Our users are expected to know better than to ask for, or offer, any diagnoses or advice in such an impersonal and unprofessional setting.Ġ7. Asking for personal recommendations where professional judgement is required is strictly prohibited. This is an online discussion forum and not a substitute for a local public health office or hospital. No professional recommendations or medical advice Questions that can be easily answered by Google or a few minutes of searching are not appropriate for e/Epidemiology.Ġ6. There is a difference between asking for help and asking for someone to do your homework for you, however. ![]() Our posting guidelines have more details.Įveryone needs help with an assignment from time-to-time. At a minimum, all posts must be relevant to epidemiology and contain at least one or more points for discussion. R/Epidemiology is intended as a place for discussion, not as a stream of consciousness. For general guidelines on posting, we recommend Rediquette as a starting set of principles. Evidence and supporting data must also be used in ways that are generally accepted as "honest" and not deceitful.Ībusive, offensive, or generally unpleasant behavior is unacceptable. ![]() No misinformation or misleading contentĬontent should be presented as objectively and with as little alteration as possible. Resources for evaluating: news stories scholarly sources & web sources.Ġ2. While citations are not strictly mandatory, it should be reasonably clear what evidence is informing a position. Individuals should be readily able to verify the comments or positions of other users. All subreddit-specific rules and policies are enforced in addition to the Reddit Content Policy. Please be mindful of our requirements for post flair, as well as any current subreddit policies. These rules apply to all content submitted to the subreddit and are enforced at moderator discretion. In an effort to establish the integrity of opinions presented within the subreddit, r/Epidemiology has established a system to help in verifying the bona fide of users posting within our community. Visit our community wiki for the most up-to-date subreddit information. ![]()
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