Are you good with statistics? Can you help?!?

Question

Please be thorough!

The National Highway Association is studying the relationship between the number of bidders on a highway project and the winning (lowest) bid for the project. Of particular interest is whether the number of bidders increases or decreases the amount of the winning bid.


Project - Number of Bidders x - Winning bid in millions y
1-9-5.1
2-9-8
3-3-9.7
4-10-7.8
5-5-7.7
6-10-5.5
7-7-8.3
8-11-5.5
9-6-10.3
10-6-8
11-4-8.8
12-7-9.4
13-7-8.6
14-7-8.1
15-6-7.8

a.Determine the regression equation. Interpret the equation. Do more bidders tend to increase or decrease the amount of the winning bid?
b.Estimate the amount of the winning bid if there were seven bidders.
c.A new entrance is to be constructed on the Ohio Turnpike. There are seven bidders on the project. Develop a 95 percent prediction interval for the winning bid.
d.Determine the coefficient of determination. Interpret its value.

Answer 1

a)
An inverse relation has a regression equation of
y = 5.72 + 13.87/x ± 2.3707
(r = 0.58757)
A straight-line regression has the formula
y = 11.23 - 0.4667x ± 2.0738
(r = -0.70638), which is a slightly better fit, but neither is a particularly good fit, as shown by the rms errors and the correlation factors

Each indicates a decrease in bid with an increase in bidders.

b)
From the linear equation, 7 bidders would result in a bid of $7.97M ± $2.07M

c)
Using the rms error (1.0369) instead of the standard deviation of the bids (σ = 1.4649), the 95% confidence interval for 7 bidders would be $5.90M < bid < $10.14M

d)
The coefficient of correlation, r = -0.70638. The coefficient of determination, then, is r^2 = 0.49897 which, as stated above, is a very poor fit.

Examination of a scatter plot of residuals indicates that there is at least one, and possibly 2 other variables involved, one of which would logically be the size of the project.

Answer 2

Throw the numbers into excel, plot the second column vs third column, right click a data point and add a regression line, it gives you the equation in the options, then you can answer the 1st and second questions, for c and d you'll need the equations for predicting with certanties.

Answer 3

Having taken fairly some college point information classes, i could tend to question any statistical consequences published everywhere. there are such fairly some vairables that for the main area, information are beside the point in serving as a correct predictor of lots of something. BB, Raji the golf green Witch

Answer 4

Decreases the lowest bid
Try it from the bidders side
bid low, supply crap work and product
just get the work and government $$$

Answer 5

Shouldn't you do your own work?