stat analysis homework and excel lab
farhm9
ic09.docCalifornia State University, Fresno Name:
DS 123, Fall 2016 MW, IC 09
New thought: If
1
then
2
2
2
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2
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1
=
=
s
s
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Measures of Center: mode, median, MEANMeasures of Spread: range, standard deviation, VARIANCE
To decide WHICH t-test of means to do, you have to know if the variances are equal.
F-Test of
Variances
If variances
equal
If variances
not equal
Do t-Test
Assuming
Equal
Variances
Do t-Test
Assuming
Unequal
Variances
VARIANCES
MEANS
Problem I. For each of the following null hypotheses and given levels,
(i) State the alternative hypothesis. (ii) Label the value of the critical bound(s) in F on the bottom axis.
(iii) Draw and shade the appropriate rejection region. (iv) State the decision rule.
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1 : 2 2 2 1 0 = s s H : A H = 0.10 n df = 10, d df = 10 Decision Rule:
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1 : 2 2 2 1 0 = s s H : A H = 0.05 n df = 6, d df = 8 Decision Rule:
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1 : 2 2 2 1 0 = s s H : A H = 0.05 n df = 7, d df = 4 Decision Rule:
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Problem II. A tree nursery is experimenting with fertilizer to increase the growth of trees A sample of 16 two-year-old pines are grown for 3 years with a cake of fertilizer buried in the soil near its roots. A second sample of 16 two-year-old pines are grown for 3 years under identical conditions without the fertilizer. Tree growth for n1 = 16 trees with fertilizer averaged
1
x
= 38.4 inches and a standard deviation of s1 = 9.8 inches. Tree growth for n2 = 16 trees without fertilizer averaged2
x
= 23.1 inches and a standard deviation of s2 = 7.4 inches.Using the 0.05 level of significance, determine whether the variances of the two samples of tree growth are equal or unequal.
I. Hypotheses: H0: HA:
II. REJECTION REGION
Draw and label the rejection region. State the decision rule.
=
n df =
d df =
III. Test Statistic:
IV. Conclusion (use a complete sentence):
V. Implication (use a complete sentence):
If you were now going to conduct a test to determine whether there was a difference in tree growth from using and from not using fertilizer, which test of means would you use? Mark the best answer.
z-test, two sample for means t-test, two sample assuming equal variances
t-test, two sample assuming unequal variances F-test, two sample for variances
