Abbreviated Interrupted Time-Series - Institute for Policy Research

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3
2
1
0
13
12
11
10
9
8
7
6
5
4
3
2
1
0
ti
ti
i
ti
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ti
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ti
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year
policy
policy
year
ratio
teacher
pupil
lunch
free
percent
m
group
year
policy
h
group
year
policy
m
group
policy
h
group
policy
m
group
year
h
group
year
m
group
h
group
year
policy
policy
year
Y
ε
τ
τ
τ
τ
β
β
β
β
β
β
β
β
β
β
β
β
β
β
+
×
+
+
+
+
+
+
×
×
+
×
×
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×
+
×
+
×
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×
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×
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=
• Full Model
• Main Variables of Interest
)
_
(
8 h
policy × group
Analytic Model –Cont.
β
ti
h
group
year
policy )
_
(
10 ×
×
β