Lab Exam 1A – Univariate and Bivariate Statistics
The spreadsheet
Exam 1A – 2009
contains
a
sample
of used 2004 Honda Accord prices and related data.
Before you do anything, save your file to the folder named “Dropbox” as
:
Exam 1A lastname
firstname.xlsx
.
Now, complete the exercises below using these data.
1.
Accord prices
– univariate distribution.
(5)
a.
First, sort the data by the variable
Price
in ascending order (smallest to largest prices).
(9)
b. Determine the
means
,
medians
, and
standard deviations
for the variables
price
and
mileage
using the
Excel functions
.
(6)
c. What do these
means
and
standard deviations
represent?
Explain
.
The means and standard deviations are our
best guesses about the true population parameter values
.
We refer to the formulas as
estimators
; we refer to the numeric values we obtain after plugging in
sample data as
estimates
.
(4)
d. Interpret the mean price you’ve calculated.
On average a used 2004 Honda Accord will be priced at $21,863. So, our estimate tells us that if we
looked at many different Honda Accords, their prices would be $21,863, on average. (This sample mean
is our best guess about the true population mean
.)
(4)
e. Interpret the standard deviation of price you’ve calculated.
On average, used 2004 Honda Accords are priced within $2,014.90 of the mean prices of $21,863. So if
we looked at many different Honda Accords, on average their prices would fall within $2,014.90 of the
mean $21,863.
(6)
f.
Create a 90% confidence interval estimate of the unknown population mean used 2004 Honda Accord
price.
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 Winter '10
 DanielLass
 Null hypothesis, true population

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