Statistics in a Modern World 800
Solutions to Practice Exam 1
-
- (iii) census: The number of all vehicle chases is reported.
- (i) 2315: 1945 is 16% less than what number? In other words, it is
84% of what number? 1945/.84=2315
- (i) year is explanatory (police chases is response)
-
- (ii) experiment: time of going to bed is imposed by researchers
- (i) time of going to bed is thought to explain how "good" sleep is
- (ii) categorical: takes values early or late
- (iv) daytime wakefulness is how researchers determine how "good" sleep
is
- (i) quantitative: "The early-to-bed group scored low on test of daytime
wakefulness..." tells us that it is assigned a number value.
- (iv) magnitude of differences is not specified, we only know they scored
"low".
- (ii) assignment to treatment groups must be random; original selection of
participants for the study seldom is random, but this is OK.
- (iii) single blind: researchers wouldn't be told who was in what group,
but subjects would certainly have an idea of whether they were sent to bed
at 10:30 pm or 2:15 am.
- (iv) lack of ecological validity is of most concern because of the
artificial setting, much like our jet lag study.
- (iii) The fact that researchers only looked at men aged 18 to 25
suggests that both gender and age may play a role in how time of going to
bed affects quality of sleep.
-
- (i) teenagers is the intended population (none of the other choices
are general enough)
-
- response
- response
- explanatory
- response
- (i) extraneous differences between high schools that did and did not
provide condoms
- (iii) rephrases the statement in the first paragraph
-
- (i) invalid: it would report the number who admit having a
STD, rather than the number who actually have one, which could be quite
different.
- (ii) reliable, so changes could be noted from year to year
-
- (ii) Late sleep=good sleep has a sample size of only 8
- (iii) the responses of interest are rather sensitive issues
-
- See paragraph 7: top number dropped 5, bottom number dropped 2, to
148 over 82
- (vi) paragraph 6 provides a chemical explanation [I gave 3 points
to people who thought it was paragraph 7.]
- (ii) See paragraph 2.
-
- American Journal of Clinical Nutrition
- 65 dieters and 62 others
- Enola or ordinary vegetable oil used
- weight and fat (lost)
- 50% more than 10 equals 15 lbs.
- (c) type of oil used would probably not be detected, but subjects
would know if they were sent to bed 4 hours later, or if they were eating
dark or white chocolate.
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