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Question

Reading To measure progress in reading ability, students

at an elementary school take a reading comprehension test

every year. Scores are measured in “grade-level” units;

that is, a score of 4.2 means that a student is reading at

slightly above the expected level for a fourth grader. The

school principal prepares a report to parents that includes

a graph showing the mean reading score for each grade. In

his comments he points out that the strong positive trend

demonstrates the success of the school’s reading program.

a) Does this graph indicate that students are making

satisfactory progress in reading? Explain.

b) What would you estimate the correlation between

Grade and Average Reading Level to be?

c) If, instead of this plot showing average reading levels,

the principal had produced a scatterplot of the reading

levels of all the individual students, would you expect

the correlation to be the same, higher, or lower? Explain.

satisfactory progress in reading? Explain.

b) What would you estimate the correlation between

Grade and Average Reading Level to be?

c) If, instead of this plot showing average reading levels,

the principal had produced a scatterplot of the reading

levels of all the individual students, would you expect

the correlation to be the same, higher, or lower? Explain.

d) Although the principal did not do a regression analy-

sis, someone as statistically astute as you might do

sis, someone as statistically astute as you might do

that. (But don’t bother.) What value of the slope of

that line would you view as demonstrating acceptable

progress in reading comprehension? Explain.

that line would you view as demonstrating acceptable

progress in reading comprehension? Explain.

Tagged in

Math

Statistics

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