## 3 Research Problem  
One crucial indicator of the effectiveness of the security control operator is the Hit Rate indicator (1). This indicator is crucial in terms of the operator's ability to perform his duties. Screening operators must be properly qualified to perform their duties. Operators must pass an exam, during which a certain value of the \(HR\) indicator must be achieved. The \(HR\) index is also evaluated periodically in subsequent years. Failure to achieve the appropriate \(HR\) index value in subsequent periodic tests results in the loss of the operator's license to perform his duties. Therefore, it is crucial to correctly estimate the value of the \(HR\) indicator, which is not being properly done today. The Hit Rate refers to the number of correct indications of images that contain a prohibited item. The number of correct indications \(n_{c}\) and the number of incorrect indications \(n_{nc}\) are collected. The collected data determine the probability of indicating images with a threat (1). \[HR=\frac{n_{c}}{n_{c}+n_{nc}} \tag{1}\]  
However, this indicator does not consider whether the operator indicated an image by seeing a threat among the objects visible on the screen; theoretically, if the operator indicated every image as a threat, it would achieve a 100% success rate. However, this is unacceptable because the security checkpoint's capacity would be too small. Any baggage marked as a threat must be searched manually. Operators are, therefore, also assessed through other indicators. They consider, for example, the probability of baggage being labeled as a hazard when there are no prohibited items in the baggage. However, these factors are not investigated in this article. The article attempts to better determine the \(n_{c}\) parameter in evaluating the \(HR\) index. In the current system, an operator is credited with a positive decision (counted with the variable \(n_{c}\)) even when the operator decides to indicate a hazard with another object in mind that is not part of the group of prohibited objects or makes his decision randomly. To test the relevance of this problem, a preliminary study was carried out, which involved surveying 10 operators completing their training as a security control operator by asking them to mark prohibited items on a sample of 100 test images, 30 of which contained a threat. TIP images collected from the real system were used for the study. The TIP system places prohibited items in random positions. Each operator was given an equal set of images to evaluate. An example of a TIP image is shown in Figure 1. Operators with little experience (up to 6 months of duties) were selected for the study. The results for this group of operators indicate that there is a large spread between the minimum and maximum error values. This highlights precisely the point of the problem. An incorrectly estimated \(HR\) index can result in the admission of people who do not meet the assumed level of the \(HR\) index. The study does not specify the required level due to the fact that it is classified information, determined by the institutions involved in certifying screening operators. The following data were collected during the study:  
* \(n_{c}\)--calculated in accordance with the applicable system;
* \(n_{ct}\)--number of true alarms (images with the threat actually identified);
* \(n_{cf}\)--number of false alarms (images with a threat where the operator has indicated another object as the threat). The \(HR\) indicator determines the Hit Rate value according to the current system. The \(HR\)' indicator determines the Hit Rate value with consideration of the eye-tracking system. The difference between the indices \(\Delta HR\) was also determined as the absolute error of the index, expressed as a percentage. The results are shown in Table 1.  
Figure 1: An example of a TIP image with the prohibited item marked with a red frame. The study results indicate that the \(HR\) would have obtained the correct value for only 1 of the 10 subjects.