A Test Constructor Is Interested in Determining the Reliability of a Certain

A test constructor is interested in determining the reliability of a certain item on a new test of aggressiveness, the ASAP (Aggressive Syndrome Assessment Profile). The items were scored 1 for showing aggressiveness and 0 for passivity. For each subject, the total score on the test is reported, high scores indicating higher levels of aggressiveness. Subj Item Score Total Score $$\begin{array}{l}\text { Subj }&\text { Item Score}&\text { Total Score }\\& \mathrm { X } & \mathrm { Y } \\1 . & 1 & 10 \\\text { 2. } & 1 & 12 \\\text { 3. } & 1 & 10 \\\text { 4. } & 1 & 11 \\5 . & 1 & 15 \\\text { 6. } & 0 & 4 \\\text { 7. } & 0 & 5 \\\text { 8. } & 0 & 6 \\\text { 9. } & 0 & 9 \\10 . & 0 & 7\end{array}$$ Find the point-biserial reliability value for the selected item.