1. A security inspector at a government building inspects about 1200 visitors ID
ID: 3170908 • Letter: 1
Question
1. A security inspector at a government building inspects about 1200 visitors ID a day. He needs toidentify whether these visitors hold a valid ID with the grant access to the building. A study wasconducted to determine how effective the security inspector was at detecting the problematic ID. Over the
course of a randomly selected inspector’s work day, 91 fake ID were hidden among the 1200 visitors that
the inspector had to examine. Whenever the inspector believes there is a fake ID, he reports seeing thefake ID item to his supervisor and requests a further inspection. The supervisor checks ID again and
records whether the inspector’s report is correct (i.e., the ID really is fake as reported by the inspector) or
incorrect (the ID is valid). The results showed that the inspector reported 83 fake ID, while the supervisorconfirmed 69 fake ID.
Please answer the following questions based on the signal detection theory
Q1: Please identify the number of signals and noise for this inspector’s job
Q2: Create the 2x2 stimulus-response matrix that shows the numbers of hits, misses, false alarms, andcorrect rejection
Explanation / Answer
a) the job of inspector is to identify the noise correctly from the given signals.
Signals here denotes the total number of visitors ID in a day therefore there are 1200 signals in a day. Out of these 91 fake IDs reported the building. Thus number of noise in inspector's job is 91.
b)
The above matrix is called the 2x2 stimulus-response matrix where the different columns are the stimulus in the form whether the ID is in reality fake or valid. It gives the following figures:
Valid ID Fake ID Allowed to pass 1095 22 Fake ID detected 14 69Related Questions
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