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API202A
Spring 2009
Assignment #1: Review of Statistics and Intro to Stata
Due February 5
th
at 5pm
(Drop in API202A mailbox inside manila envelope with your KSG mailbox # written outside)
The purpose of this exercise is to help you review some key concepts from API201 and to become familiar
with Stata. The assignment has 2 parts: Part I does not require Stata, while Part II does.
We have provided
a Stata tutorial which will enable you to practice the commands you will need in order to complete this
assignment.
The Stata tutorial is posted on the course page, together with this assignment.
PART I – REVIEW OF STATISTICAL CONCEPTS FROM API201
In this part of the assignment, we examine math test scores for a sample of California school districts.
The
appendix to this assignment, which reviews some of the relevant material from API201, including
formulas, may be helpful as you work through the questions.
Basic summary statistics for math test scores and the number of computers per student, by district, are
reported below.
sum math_scr comp_stu
Variable 
Obs
Mean
Std. Dev.
Min
Max
+
math_scr 
420
653.3426
18.7542
605.4
709.5
comp_stu 
420
.1359266
.0649558
0
.4208333
1.
Using this table and your knowledge of API201, report the following statistics.
a)
Mean math test score (
X
) =
b)
Variance of math test score (
2
X
S
) =
c)
Variance of mean math test score (
2
X
S
) =
d)
Standard error of mean test score (
X
S
) =
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2.
Estimate a 95% confidence interval for the mean math test score in this sample.
3.
Some education analysts have speculated that access to computers can increase math achievement.
Let’s
compare the average math test scores of
computerintensive
districts (defined as having a computer per
student ratio above the median) with the rest of the districts.
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 Spring '09
 LEVY
 Statistics, Normal Distribution, Null hypothesis, Statistical hypothesis testing, math test scores

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