For each of the following, decide whether the proper inference is a prediction interval for y or a confidence interval for E(v) : (a) A jeweler wants to predict the selling price of a diamond stone on the basis of its size (number of carats).   (b) A psychologist wants to estimate the average IQ of all patients who have a certain income level.

It is assumed that standardized test scores should be correlated with students' classroom performance. One would expect that students who consistently perform well in the classroom (on tests, quizzes, etc.) would also perform well on a standardized test scored from 0-100 (with 100 indicating high achievement). A teacher decides to examine this hypothesis. At the end of the academic year, she collects the following data for her (admittedly small) class: Standardized test score Overall GPA 56 1.8 1 73 2.6 2 78 2.9 3 83 2.9 4 85 3.0 5 rows x 2 columns What is your best guess for the expected GPA of a student who scored a 88 on the standardized test? number (rtol=0.01, atol=0.0001) Determine a 95% confidence interval for the expected GPA of a student who scored a 76 on the standardized test. Ib number (rtol=0.01, atol=0.0001) ub number (rtol=0.01, atol=0.0001)

Consider the following difference-in-differences estimator for the effect of a newgarbage incinerator on housing values. Rumor of a new incinerator being built in a townin Massachusetts began after 1978, and construction began in 1981. You have data onprices of houses that sold in 1978, and another sample of those that sold in 1981. Youdefine a dummy variable (y81) as equal to 1 if the house sold in 1981, and zero if thehouse sold in 1978. Your hypothesis is that the price of houses located near theincinerator will fall across those years relative to the price of more distant houses. Youdefine a house as being near the incinerator (nearinc) if it is within 3 miles of it. Housingprice (price) is measured in real terms, in 1978 dollars. You estimate the followingregression (standard errors are in parentheses): price = 82,517.23 + 18,790.29y81 -18,824.37nearinc            (2,726.91)      (4,050.07)       (4,875.32)  -11,863.90(y81 * nearinc)  (7,456.65) n=321   Interpret the coeffiecient…

The weekly expenditure on groceries of a random sample of 100 family households was recorded. It was estimated that the mean expenditure was approximately $240. With rising interest rates and petrol prices, it was anticipated that grocery expenditure might decrease. Which hypothesis test would you use to test this claim? 1.One tailed, one sample t-test 2.Two tailed, one sample t-test 3.One tailed, z-test 4.One-tailed Paired Samples t-test 5.Chi Square