Activity 8_2: Instrument Reliability (1) A reliable instrument is one that is consistent in what it measures. If an individual scores highly on the first administration of a test: for example: he or she should: if the test is reliable, score highly on a second administration. In this activity, you are going to evaluate the reliability of an instrument. Imagine that you are conducting a study for which you must develop a mastery test in mathematics for ninth-grade students. You develop a 30-point test and distribute it to a class of 13 in a certain school district on the west coast of the United States in May of 2004. You then give the test agam one month later to the day in 2004 The scores ofthe students on the two administrations of the test are showm below. Plot each pair of scores on the scatterplot started below. We have entered "A ' s" scores to get you started. What do they suggest to you about the reliability of this? Explain. 30-POINT MATHEMATICS MASTERY TEST (FIRST ADMINISTRATION) 17 25 12 28 27 21 24 27 21 10 30-POINT MATHEMATICS MASTERY TEST (SECOND ADMINISTRATION) 15 18 21 15 14 27 24 25 21 27 19 15