Assignment Stats 250 W11 HW 9
Required Assignment Stats 250 W11 HW 9
Question
1
(Chapter
14)
Correlation:
Match each of the three graphs (A – C) below to one of three possible correlations:
r = 0.4, r=0, r=0.9
1.
Graph A: r = 0.4, Graph B: r = 0, Graph C: r = 0.9
2.
Graph A: r = 0.4, Graph B: r = 0.9, Graph C: r = 0
3.
Graph A: r = 0, Graph B: r = 0.9, Graph C: r = 0.4
4.
Graph A: r = 0, Graph B: r = 0.4, Graph C: r = 0.9
5.
Graph A: r = 0.9, Graph B: r = 0, Graph C: r = 0.4
6.
Graph A: r = 0.9, Graph B: r = 0.4, Graph C: r = 0
Solution:
6. Graph A: r = 0.9, Graph B: r = 0.4, Graph C: r = 0
Question
2
(Chapter
Crawling Age for Babies. Researchers at an Infant
Study Center wondered whether temperature
might influence age at which babies learn to crawl.
Perhaps the extra clothing that babies wear in cold
weather would restrict movement and delay the
age at which they started crawling.
Data were collected on infant boys and girls.
Parents reported the month of the baby’s birth and
the age (in weeks) at which their child first
crawled. The table below gives the average
Temperature (°F) when the babies were 6 months
old and the average Crawling Age (in weeks) for
each month of the year. A scatterplot and a
regression analysis were completed with SPSS and
shown below.
Model Summary
Model
R
R Square
Adjusted R Square
Std. Error of the Estimate
6
Average
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View Full Documenta.
Provide the value to complete the sentence: Based on the analysis above, about ________% of the
variation in the average crawling age can be explained by the linear relationship it has with 6month
temperature.
Your Answer:
61.8
Solution:
61.8
(this question is asking for the value of
r
2
)
b.
Give the value of the correlation between average crawling age and 6month temperature.
Your Answer:
0.786
Solution:
r = 0.786
c.
Give the least square regression line for estimating the average crawling age from the 6month
temperature.
Your Answer:
=(bo)+(b1)x
Average crawling age = 36.133 + 0.085(6month temperature)
Solution:
= 36.133  0.085(x) or in words, predicted crawling age = 36.133 – 0.085(temp)
d.
For babies born in August, the average temperature when they were 6 months old (so in February) was
30°F. For such babies in the sample, the average crawling age was 32.82 weeks. Find the corresponding
residual for this observation. Show all work and include your units.
Your Answer:
Average crawling age = 36.133 + .085(6month temperature)
x=30
=36.133 + .085*30 = 33.583
Model
R
R Square
Adjusted R Square
Std. Error of the Estimate
1
.786
.618
.579
1.14181
ANOVA
Model
Sum of Squares
df
Mean Square
F
Sig.
1 Regression
21.059
1
21.059
16.153
.002
Residual
13.057
10
1.304
Total
34.096
11
Coefficients
Model
Unstandardized
Coefficients
Standardized
Coefficients
tS
i
g
.
B
Std. Error
Beta
1
(Constant)
36.133
1.134
31.859 .000
6month
Temp
.085
.021
.786
4.019 .002
Birth
Month
6
Month
Temp
Average
Crawling
Age
Jan
66
29.84
Feb
73
30.52
Mar
72
29.70
Apr
63
31.84
May
62
28.58
Jun
39
31.44
Jul
33
33.64
Aug
30
32.82
Sep
33
33.83
Oct
37
33.35
Nov
48
33.38
Dec
57
32.32
4/17/2011
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 Winter '10
 Gunderson
 Correlation, Linear Regression, Regression Analysis, R Square, average crawling age

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