Incidence = number of new cases / number of people at risk in a given period of time.
This question does not give you enough data because we do not know the total number of people at risk, we do not know if some of these people had cararacts prior and thus would not be considered in the at risk population, and we do not know which are new diagnoses (let alone the amount of new diagnoses total in the year since it is supposed to be an annual incidence).
Basically, this could be used to estimate prevalence but incidence is not the same.
I got hung up on the term "visual SCREENING" and therefore made the logical leap that meant that these 4000 people were not yet showing symptoms. I made my calculations and got myself fooled.
submitted by โcassdawg(1780)
Incidence = number of new cases / number of people at risk in a given period of time.
This question does not give you enough data because we do not know the total number of people at risk, we do not know if some of these people had cararacts prior and thus would not be considered in the at risk population, and we do not know which are new diagnoses (let alone the amount of new diagnoses total in the year since it is supposed to be an annual incidence).
Basically, this could be used to estimate prevalence but incidence is not the same.