The College Board, administrator of the SAT test for college entrants, has made several changes to the test in recent years. One recent change occurred between years 2005 and 2006. In a press release, the College Board announced SAT scores for students in the class of 2005, the last to take the former version of the SAT featuring math and verbal sections. The board indicated that for the class of 2005, the average SAT math scores continued their strong upward trend, increasing from 518 in 2004 to 520 in 2005, 14 points higher than 10 years ago and an all-time high. The file titled MathSAT contains the math SAT scores for the interval 1967 to 2005.
a. Produce a time-series plot for the combined gender math SAT scores for the period 1980 to 2005. Indicate the time-series components that exist in the data.
b. Conduct a test of hypothesis to determine if the average SAT math scores of students continued to increase in the period indicated in part a. Use a significance level of 0.10 and the test statistic approach.
c. Produce a forecast for the average SAT math scores for 2010.d. Beginning with the March 12, 2005, administration of the exam, the SAT Reasoning Test, was modified and lengthened. How does this affect the forecast produced in part c? What statistical concept is exhibited by producing the forecast in part c?