Answer: Test–retest reliability
Explanation:
Test-Retest reliability is defined as the method in which test is performed with same condition and factors for same measure in successive order so that closeness and reliability of the test results can be determined over the time.It is also known as retest reliability.
As per the mentioned situation, Tara is using he test-retest reliability asses for happiness testing.She is testing the happiness measure two times with the same group of people in same condition for gaining the outcomes to compare.