Morning or evening? Are you a morning person, an evening person, or neither? Doe

Question

Morning or evening? Are you a morning person, an evening person, or neither? Does this personality trait affect how well you perform? A random sample of 100 students took a psychological test that found 16 morning people, 30 evening people, and 54 who were neither. All the students then took a test of their ability to memorize at 8:00AM, and again at 9:00 P.M. The response variable is the score at 8:00 AM, minus the score at 9:00 P.M. Writing essays Do strategies such as preparing a written outline help students write better essays? College students were divided at random into four groups of 20 students each, then asked to write an essay on an assigned topic. Group A (the control group) received no additional instruction. Group B was required to prepare a written outline. Group C was given 15 ideas that might be relevant to the essay topic, Group D was given the ideas and also required to prepare an outline. An expert scored the quality of the essays on a scale 1 to 9. Test accommodations Many states require school children to take regular statewide tests to assess their progress. Children with learning disabilities who read poorly may not do well on mathematics tests because they can't read the problems. Most states allow "accommodations" for learning-disabled children. Randomly assign l00 learning disabled children in equal numbers to three types of accommodation and a control group: math problems are read by a teacher; by a computer; by a computer that also shows a video; and standard test conditions. Compare the mean scores on the state mathematics assessment. A medical study The Quebec (Canada) Cardiovascular Study recruited men aged 34 to 64 at random from towns in the Quebec City metropolitan area. Of these, 1824 met the criteria (no diabetes, free of heart disease, and so on) for a study of the relation- ship between being overweight and medical risks. The 719 normal-weight men had a mean triglyceride level of 1.5 millimoles per liter (mmoI/A) of blood, the 885 overweight men had mean 1.7 mmol/l and the 220 obese men had mean 1.9 mmol/l.

Explanation / Answer

7. Morning or Evening?

Parameter of interest= The difference of psychological test score between 8.00 AM and 9.00 PM.

Number of groups, k = 3

n1 = 16

n2 = 30

n3 = 54

N = 16 + 30 + 54 = 100

Degrees of Freedom for F-statistic is given as (k-1,N-k) = (3-1,100-3) = (2,97)

8. Writing essays

Parameter of interest = Expert score

Number of groups, k = 4

n1 = 20

n2 = 20

n3 = 20

n4 = 20

N = 20 + 20 + 20 + 20 = 80

Degrees of Freedom for F-statistic is given as (k-1,N-k) = (4-1,80-4) = (3,76)

9. Test accomodations

Parameter of interest= State mathematics assessment

Number of groups, k = 4

n1 = 25

n2 = 25

n3 = 25

n4 = 25

N = 25 + 25 + 25 +25 = 100

Degrees of Freedom for F-statistic is given as (k-1,N-k) = (4-1,100-4) = (3,96)

10. Medical study.

Parameter of interest= Triglyceride

Number of groups, k = 3

n1 = 719

n2 = 885

n3 = 220

N = 719 + 885 + 220 = 1824

Degrees of Freedom for F-statistic is given as (k-1,N-k) = (3-1,1824-4) = (2,1820)

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