(b) Calculate the t-statistics of the coefficient of AADT (b = 0.002) using the following equation: /SSE/(n – 2) VE:(x; – x)² where x, = observed AADT for segment i; x = average observed AADT for all segments. Assess statistical significance of the coefficient b at a 95% confidence interval using hypothetical testing. Assume null hypothesis (Ho): b is not statistically different from zero and alternative hypothesis (H1): b is statistically different from zero. Sketch a t-distribution curve and show 1) the calculated t-statistics; 2) the critical values of t-statistics (tent0.025 = 2.01 for sample size = 48); and 3) the confidence interval in the sketch.

Linear Algebra: A Modern Introduction
4th Edition
ISBN:9781285463247
Author:David Poole
Publisher:David Poole
Chapter7: Distance And Approximation
Section7.3: Least Squares Approximation
Problem 31EQ
icon
Related questions
Question
plz solve question (b) with explanation within 30-40 mins and get upvotes.
crash
329
201
263
170
AADT
Question 3 (
The records of crash frequency and annual average daily traffic volume (AADT) in 2009-2012
were collected from 48 roadway segments of Highway 401 between Windsor and London in
Ontario. The data are stored in data-2009-2012.txt posted on Blackboard. A crash frequency
model was developed to predict the number of crashes based on AADT using a linear regression
model as follows:
103600
107300
107300
107500
97100
125600
71900
53000
46000
43600
479
160
257
87
65
132
58
32
53
70
64
y = -13.1 + 0.002 * x
45700
45700
59900
68400
66600
where y = crash frequency (“crash" in the file) and x = AADT.
(a) Plot the graphs of the observed crash frequencies (x-axis) and the predicted crash frequencies
using the above linear regression model (y-axis) in a scatter chart. Calculate the value of R
using the following equations:
103
52
63100
47
47
65700
63400
65700
83
54
66100
69700
R² =1- SSE
SST
68
71
68100
69600
96
64
20
50
85
79
66500
55700
where SSE = the sum of squares of errors (or the unexplained variance by the model), SST =
the total variance in the data, y,= observed crash frequency for segment i; ŷ,= the predicted
27000
26700
crash frequency for segment i; ỹ= average observed crash frequency for all segments; and n
= number of segments (= 48).
26400
24000
22400
11
(b) Calculate the t-statistics of the coefficient of AADT (b = 0.002) using the following equation:
38
49
23100
21300
42
17
21300
21800
23400
21500
SSE/(n – 2)
E:(xi – x)²
53
73
where x = observed AADT for segment i; x = average observed AADT for all segments.
70
85
36
66
18100
19300
21000
Assess statistical significance of the coefficient b at a 95% confidence interval using
hypothetical testing. Assume null hypothesis (Ho): b is not statistically different from zero and
alternative hypothesis (H1): b is statistically different from zero. Sketch a t-distribution curve
and show 1) the calculated t-statistics; 2) the critical values of t-statistics (tenit,0.025 = 2.01 for
sample size = 48); and 3) the confidence interval in the sketch.
21900
31
24
17
20900
24000
22400
22200
20200
17300
12100
6450
44
25
18
7
(c) Based on the sign of the coefficient b, discuss the effect of AADT on crash frequency. Is the
effect realistic? Explain.
1
Transcribed Image Text:crash 329 201 263 170 AADT Question 3 ( The records of crash frequency and annual average daily traffic volume (AADT) in 2009-2012 were collected from 48 roadway segments of Highway 401 between Windsor and London in Ontario. The data are stored in data-2009-2012.txt posted on Blackboard. A crash frequency model was developed to predict the number of crashes based on AADT using a linear regression model as follows: 103600 107300 107300 107500 97100 125600 71900 53000 46000 43600 479 160 257 87 65 132 58 32 53 70 64 y = -13.1 + 0.002 * x 45700 45700 59900 68400 66600 where y = crash frequency (“crash" in the file) and x = AADT. (a) Plot the graphs of the observed crash frequencies (x-axis) and the predicted crash frequencies using the above linear regression model (y-axis) in a scatter chart. Calculate the value of R using the following equations: 103 52 63100 47 47 65700 63400 65700 83 54 66100 69700 R² =1- SSE SST 68 71 68100 69600 96 64 20 50 85 79 66500 55700 where SSE = the sum of squares of errors (or the unexplained variance by the model), SST = the total variance in the data, y,= observed crash frequency for segment i; ŷ,= the predicted 27000 26700 crash frequency for segment i; ỹ= average observed crash frequency for all segments; and n = number of segments (= 48). 26400 24000 22400 11 (b) Calculate the t-statistics of the coefficient of AADT (b = 0.002) using the following equation: 38 49 23100 21300 42 17 21300 21800 23400 21500 SSE/(n – 2) E:(xi – x)² 53 73 where x = observed AADT for segment i; x = average observed AADT for all segments. 70 85 36 66 18100 19300 21000 Assess statistical significance of the coefficient b at a 95% confidence interval using hypothetical testing. Assume null hypothesis (Ho): b is not statistically different from zero and alternative hypothesis (H1): b is statistically different from zero. Sketch a t-distribution curve and show 1) the calculated t-statistics; 2) the critical values of t-statistics (tenit,0.025 = 2.01 for sample size = 48); and 3) the confidence interval in the sketch. 21900 31 24 17 20900 24000 22400 22200 20200 17300 12100 6450 44 25 18 7 (c) Based on the sign of the coefficient b, discuss the effect of AADT on crash frequency. Is the effect realistic? Explain. 1
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 4 steps with 4 images

Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Linear Algebra: A Modern Introduction
Linear Algebra: A Modern Introduction
Algebra
ISBN:
9781285463247
Author:
David Poole
Publisher:
Cengage Learning
College Algebra
College Algebra
Algebra
ISBN:
9781337282291
Author:
Ron Larson
Publisher:
Cengage Learning
Glencoe Algebra 1, Student Edition, 9780079039897…
Glencoe Algebra 1, Student Edition, 9780079039897…
Algebra
ISBN:
9780079039897
Author:
Carter
Publisher:
McGraw Hill