Question

answer please Q 14

to an expected syn- chrony score of 7.76; they then reported arscore of 2.27 for this difference. This esult is statistically significant at p<05. Explain this result to a person who is familiar with hypothesis testing with a known population variance but not with for the 30 I A researcher conducts a study of perceptual illusions under two different lighting con- ditions Twenty participants were each tested under both of the two different condi- ons. The experimenter reported: "The mean number of effective illusions was 6.72 nder the bright conditions and 6.85 under the dimly lit conditions, a difference that 825 not significant, (19) = 1.62." Explain this result to a person who has never had a course in statistics. Be sure to use sketches of the distributions in your answer. e/ test for a single sample. the tch ho for Set I all, 12 In each of the following studies, a single sample's mean is being compared to a population with a known mean but an unknown variance. For each study, decide whether the result is significant. Estimated Population Standard Deviation (S) Population Mean Sample Size (M) Sample Mean (M) Significance Level Stuty Tails 16 100.31 2.00 100.98 1 (high predicted 05 16 47 4.00 .00 cnt .05 16 68.90 9.00 34.00 1 (ow predictedy .01 13. Evolutionary theories often emphasize that humans have adapted to their physical environment. One such theory hypothesizes that people should spontaneously fol- low a 24-hour cycle of sleeping and waking-even if they are not exposed to the usual pamern of sunlight. To test this notion, eight paid volunteers were placed (individu- ally) in a room in which there was no light from the outside and no clocks or other indications of time. They could turn the lights on and off as they wished. After a month in the room, each individual tended to develop a steady cycle. Their cycles at the end of the study were as follows: 25, 27, 25, 23, 24, 25, 26, and 25. Using the .05 level of significance, what should we conclude about the the- ory that 24 hours is the natural cycle? (That is, does the average cycle length under these conditions differ significantly from 24 hours?) (a) Use the steps of ypothesis testing. (b) Sketch the distributions involved. (c) Explain your answer to someone who has never taken a course in statistics. 14. In a particular country, it is known that college seniors report falling in love an average of 2.20 times during their college years. A sample of five seniors, origi- nally from that country but who have spent their entire college career in the United States, were asked how many times they had fallen in love during their college years. Their numbers were 2, 3, 5, 5, and 2. Using the .05 significance level, do students like these who go to college in the United States fall in love more often than those from their country who go to college in their own country? (a) Use the seps of hypothesis testing. (b) Sketch the distributions involved. (c) Explain your answer to someone who is familiar with the Z test (from Chapter 6) but is not Tamiliar with the t test for a single sample.

Answer 1

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