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# STATS Problems with Solution

Question # 00013188
Subject: Statistics
Due on: 05/12/2014
Posted On: 04/22/2014 07:30 PM

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Statistics Extra Practice

-These are hypothesis tests. You must determine which test to perform and which test statistic to calculate. Show all work, step by step, calculations labeled. Round to 2 decimal pages; do not round values obtained from tables.

Three problems:

1. A sample of freshmen takes a reading comprehension test and their scores are summarized below. If the mean for the general population on this test is ?=12, can you conclude that this sample is significantly different from the population?

Sample scores: 16, 8, 8, 6, 9, 11, 13, 9, 10

a. Conduct a hypothesis test with ?=.05.
b. Write up the results using APA format.

2. A psychologist studies the effect of frequent testing on perception of course material. In one of the professor’s sections, students are given quizzes each week. The second section receives only two tests during the semester. At the end of the semester, both sections receive the same questionnaire. Summarized below is a random sample of the perception scores from 9 students in each section.

Frequent Quizzes: 4, 8, 3, 10, 5, 6, 6, 2, 10
Two Exams: 5, 7, 9, 9, 10, 10, 12, 14, 14

a. Do the data indicate that testing frequency has a significant effect on performance? Conduct a hypothesis test with ?=.05.
b. Compute r2 to measure the size of the effect.
c. Compute a 90% confidence interval to estimate the population mean difference.
d. Write up your results using APA format.

3. A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers. For a week prior to training, each subject records the number of headaches suffered. Subjects then receive relaxation training and for the week following training the number of headaches is again measured. The change in number of headaches before and after training (differences scores) is as follows (minus indicates a reduction in number of headaches):

Difference scores: -5, -1, -4, -3, -6, -8, 0, +1, -1

a. Is there an effect of relaxation training? Conduct a hypothesis test with ?=.05.
b. Compute Cohen’s d to measure the size of the effect.
c. Write up the results using APA format.

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#### STATS Problems with Solution

Tutorial # 00012743
Posted On: 04/22/2014 07:31 PM
Posted By:
vikas
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Tutorial Preview ……
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STATS_Problems_with_Solution_(2).docx (16.9 KB)
Preview: results xxxxx APA xxxxxx An independent xxxxxx t-test was xxxxxxxxx to xxxxxxxxx xxxxxxx frequency xx tests affect xxxxxxxxxxx performance Results xxxxxxxxx that xxx xxxxxxxxxx between xxxx perception score xxx students giving xxxxxxxxx quizzes xx x 6, xx = 2 xxx n = xx and xxxxx xxxxxx only xxx exams (M x 10, SD x 3, x x 9) xxx statistically significant, xxxxx = -2 xxx p xxxx x 05, xx 90 (-6 xxx -1 58), xxx = x xx 3 x researcher would xxxx to determine xx relaxation xxxxxxxx xxxx affect xxx number of xxxxxxxxx for chronic xxxxxxxx sufferers xxx x week xxxxx to training, xxxx subject records xxx number xx xxxxxxxxx suffered xxxxxxxx then receive xxxxxxxxxx training and xxx the xxxx xxxxxxxxx training xxx number of xxxxxxxxx is again xxxxxxxx The xxxxxx xx number xx headaches before xxx after training xxxxxxxxxxxx scores) xx xx follows xxxxxx indicates a xxxxxxxxx in number xx headaches):Difference xxxxxxx xxx -1, xxx -3,.....
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Available for
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#### STATS Problems with Solution

Tutorial # 00012744
Posted On: 04/22/2014 07:32 PM
Posted By:
vikas
Questions:
4722
Tutorials:
4991
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Tutorial Preview …test xxxx ?= xx Ho: µ1 x µ2Ha: µ1? xxxxxxxxxxxxxxx level: x xxxxxxxx = xxxxxxxxxxxxxxxxxxxxxxx = 6s1 x sqrt(((4-6)^2+(8-6)^2+(3-6)^2+(10-6)^2+(5-6)^2+(6-6)^2+(6-6)^2+(2-6)^2+(10-6)^2)/(9-1)) = x 87n1 x xxxxxxx = xxxxxxxxxxxxxxxxxxxxxxxxxx = 10s2 x sqrt(((5-10)^2+(7-10)^2+(9-10)^2+(9-10)^2+(10-10)^2+(10-10)^2+(12-10)^2+(14-10)^2+(14-10)^2)/(9-1))= 3n2 x 9t-statistics x xx - xxxxxxxxxxx 87^2 + xxxxxxx = -2 xxxx = xxx x 2 x 16p-value = x 011Critical values: xx 12, x xxxxxxxxxxx region: x < -2 xx or t xxxx 2 xxxx xx rejected xx test statistic xxxxx in rejection xxxxxx There xx xxxxxxxxxx evidence xxxx testing frequency xxxxxxx performance b xxxxxxx r2 xx xxxxxxx the xxxx of the xxxxxx r² = x 89^2 x xx 89^2 x 16) = x 34This indicates x large xxxxxx xxxx c xxxxxxx a 90% xxxxxxxxxx interval to xxxxxxxx the xxxxxxxxxx xxxx difference xxx 90% confidence xxxxx with df x 16, xxxxxxx x 1 xxxxxxxx confidence level x (6 - xxx - x xxx *sqrt((2 xxxx + 3^2)/9) x -6 42Upper xxxxxxxxxx level x xx - xxx + 1 xxx *sqrt((2 87^2 x 3^2)/9) x xx 58So, xxx confidence interval xxx population mean xxxxxxxxxx is…
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STATS_Problems_with_Solution_(2).docx (16.9 KB)
Preview: exams xx = xxx SD = xx n = xx was xxxxxxxxxxxxx xxxxxxxxxxxx t(16) x -2 89, x < 0 xxx CI xx xxx 42, xx 58), r² x 0 32 x A xxxxxxxxxx xxxxx like xx determine if xxxxxxxxxx training will xxxxxx the xxxxxx xx headaches xxx chronic headache xxxxxxxxx For a xxxx prior xx xxxxxxxxx each xxxxxxx records the xxxxxx of headaches xxxxxxxx Subjects xxxx xxxxxxx relaxation xxxxxxxx and for xxx week following xxxxxxxx the xxxxxx xx headaches xx again measured xxx change in xxxxxx of xxxxxxxxx xxxxxx and xxxxx training (differences xxxxxxx is as xxxxxxx (minus xxxxxxxxx x reduction xx number of xxxxxxxxxxxxxxxxxxxxx scores: -5, xxx -4, xxx xxx -8, xx +1, -1a xx there an xxxxxx of xxxxxxxxxx xxxxxxxxx Conduct x hypothesis test xxxx ?= 05 xxx µD x xxxx µD x 0Significance level: x 05mean difference x (-5-1-4-3-6-8+0+1-1)/9 x xxx = xxxxxxxxxxxxxx + (-1+3)^2 x (-4+3)^2 + xxxxxxxx + xxxxxxxx x (-8+3)^2 x (0+3)^2 +.....
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