기본적인 통계에 지식이 없습니다.
문제 풀어주실분 있으시면 답변 부탁드려요. 한글로 적어주셔도 됩니다.
관련링크 있으시면 알려주시면 감사하겠습니다.
2.
A colleague of yours has suggested a new way to measure the variability (or “spread-outness”) of the data you are studying. They suggest the following formula for the data values you are studying. They also state that you add every other data value, and every other”error“in the numerator.
In case you have 8 data values, for example, they suggest you proceed as follows:
x
1
+ (
x
2
− x
) +
x
3
+ (
x
4
− x
) +
x
5
+ (
x
6
− x
) +
x
7
+ (
x
8
− x
)
d
=
8
a
What might cause issues with this approach?
b
How does this compare with the M.A.D.?
Regression and Estimation
3.
A colleague decides that they would like to use a regression model to predict a variable,
Y
, as a
response
to a variable,
X
a.
For a value of
x
= 7, what would you predict as the corresponding
y
value?
b.
For a value of
x
= 9, what would you predict as the corresponding
y
value?
c.
For the
y
value you found in
a.
above, give an estimate of the likely range or variability in the possible values of
y
that we might observe.
d.
Does this model give a good prediction of
y
in response to
x
? Why or why not?
4.
A regression model is built to predict the pH pf well water from Bicarbonate content in p.p.m. After performing the work in Excel, the following results are obtained:
Coefficients
Intercept 432.15 Slope -37.78
a.
At a pH of 7.3, what is the estimated Bicarb in p.p.m.?
b.
Is this scatterplot reflective of a strong relationship between pH and Bicarb? Why or why not?
c.
Is it fair to say the Intercept of 432.15 is reflective of the Bicarb at a pH of 0? If so why? If not, why not?
d.
Consider the putput given below:
Regression Statistics
R Square 0.115
Observations 34
Is
y
=
−
37
.
78 + 432
.
15 a good prediction model for Bicarb in p.p.m. as a response to pH? Why or Why not?
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