Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Craftybutterfly on 07/06/2015 05:50:37

Title: How do you interpret an ovulation test result?
Post by: Craftybutterfly on 07/06/2015 05:50:37

If someone got a positive ovulation test but then did not get a period would that mean that the test was a false positive?

Title: Re: Random question
Post by: evan_au on 07/06/2015 11:36:23

Could that mean that someone is pregnant?

Title: Re: How do you interpret an ovulation test result?
Post by: Pecos_Bill on 07/06/2015 19:03:22

This is a question of the test's sensitivity versus its specificity.

Substituting ovulation for disease, then...


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Sensitivity:

If a person has a disease, how often will the test be positive (true positive rate)?


Put another way, if the test is highly sensitive and the test result is negative you can be nearly certain that they don’t have disease.


A Sensitive test helps rule out disease (when the result is negative). Sensitivity rule out or "Snout"

Sensitivity= true positives/(true positive + false negative)

Specificity:

If a person does not have the disease how often will the test be negative (true negative rate)?


In other terms, if the test result for a highly specific test is positive you can be nearly certain that they actually have the disease.


A very specific test rules in disease with a high degree of confidence Specificity rule in or "Spin".

Specificity=true negatives/(true negative + false positives)

Predictive value for a positive result (PV+):

PV+ asks " If the test result is positive what is the probability that the patient actually has the disease?"

PV+= true positive/(true positive + false positive)
Predictive value for a negative result (PV-):

PV- aks " If f the test result is negative what is the probability that the patient does not have disease?"


PV-= true negatives/(true negatives +false negatives)

https://www.med.emory.edu/EMAC/curriculum/diagnosis/sensand.htm