Ask a question from expert

Ask now

Report on Experiment Test Hypothesis

53 Pages8860 Words745 Views
   

Added on  2020-04-15

Report on Experiment Test Hypothesis

   Added on 2020-04-15

BookmarkShareRelated Documents
Exercise 11:1.An experiment is conducted to test the claim that James Bond can taste the differencebetween a Martini that is shaken and one that is stirred. What is the null hypothesis?SolutionNull hypothesis (H0) is that James Bond cannot taste the difference between a Martinithat is shaken and one that is stirred. 2.The following explanation is incorrect. What three words should be added to make itcorrect?The probability value is the probability of obtaining a statistic as different (or moredifferent/extreme) from the parameter specified in the null hypothesis as the statisticobtained in the experiment. The probability value is computed assuming that the nullhypothesis is true.3.Why do experimenters test hypotheses they think are false?SolutionTo establish directionality.To place the burden of proof on the alternative4.State the null hypothesis for:a.An experiment testing whether echinacea decreases the length of colds.SolutionH0: Echinacea does not have an effect on the length of coldsb.A correlational study on the relationship between brain size and intelligence.SolutionH0: Brain size is not correlated with intelligence (H0:r=0¿
Report on Experiment Test Hypothesis_1
c.An investigation of whether a self-proclaimed psychic can predict the outcome of acoin flip.SolutionH0: Self-proclaimed psychic cannot predict the outcome of a coin flipd.A study comparing a drug with a placebo on the amount of pain relief. (A one tailedtest was used).SolutionH0: There is no difference in the amount of pain relief by placebo and drug.5.Assume the null hypothesis is that μ = 50 and that the graph shown below is the samplingdistribution of the mean (M). Would a sample value of M= 60 be significant in a two-tailed test at the .05 level? Roughly what value of M would be needed to be significant?SolutionYes a sample of M = 60 would be significant in a two-tailed test at the 0.05 level.Roughly the M value should be less than or equal to 40 or greater than or equal to 60. 6.A researcher develops a new theory that predicts that vegetarians will have more of aparticular vitamin in their blood than non-vegetarians. An experiment is conducted andvegetarians do have more of the vitamin, but the difference is not significant. Theprobability value is 0.13. Should the experimenter's confidence in the theory increase,decrease, or stay the same? SolutionHis confidence should increase that the null hypothesis is false
Report on Experiment Test Hypothesis_2
7.A researcher hypothesizes that the lowering in cholesterol associated with weight loss isreally due to exercise. To test this, the researcher carefully controls for exercise whilecomparing the cholesterol levels of a group of subjects who lose weight by dieting with acontrol group that does not diet. The difference between groups in cholesterol is notsignificant. Can the researcher claim that weight loss has no effect? SolutionThe researcher cannot claim that weight loss has no effect, only that the data do notsupport the hypothesis.8.A significance test is performed and p = .20. Why can't the experimenter claim that theprobability that the null hypothesis is true is .20?SolutionThe p-value just indicates the probability of obtaining a particular statistic only (where inthis case, a proportion) from the sample data under the assumption that the nullhypothesis is true. This is NEVER the same as saying the probability of the nullhypothesis being true is.20.9.For a drug to be approved by the FDA, the drug must be shown to be safe and effective.If the drug is significantly more effective than a placebo, then the drug is deemedeffective. What do you know about the effectiveness of a drug once it has been approvedby the FDA (assuming that there has not been a Type I error)? Solution
Report on Experiment Test Hypothesis_3
10.When is it valid to use a one-tailed test? What is the advantage of a one-tailed test? Givean example of a null hypothesis that would be tested by a one-tailed test.SolutionAdvantage of a one-tailed testThe advantage of adopting the one-tailed test is an improvement in power to reject thenull hypothesis if the null hypothesis is truly false.Example;Null hypothesis (H0): The average weight of students is less than 60 kilograms (i.e.H0:μ<60¿.11.Distinguish between probability value and significance level. SolutionTheprobability value(also called the p-value) is the probability of the observed resultfound in your research study of occurring (or an even more extreme result occurring),under the assumption that the null hypothesis is true (i.e., if the null were true). On theother hand, thesignificance level(also called the alpha level) is the cutoff value theresearcher selects and then uses to decide when to reject the null hypothesis.12.Suppose a study was conducted on the effectiveness of a class on "How to take tests."The SAT scores of an experimental group and a control group were compared. (Therewere 100 subjects in each group.) The mean score of the experimental group was 503 and
Report on Experiment Test Hypothesis_4
the mean score of the control group was 499. The difference between means was found tobe significant, p = .037. What do you conclude about the effectiveness of the class? SolutionIf you set alpha =.05: There is sufficient evidence to reject the null hypothesis that thereis no difference between the groups, since p<.05. There is a significant differencebetween the mean score of the groups.13.Is it more conservative to use an alpha level of .01 or an alpha level of .05? Would betabe higher for an alpha of .05 or for an alpha of .01? SolutionChoosing a lower significance level, alpha, is more conservative in that you are lesslikely to reject the null hypothesis when it is true. Generally, in biostatistics applications,making a type I error (e.g. declaring a new treatment beneficial when in truth it is not) ismore serious than making a type II error (e.g. failing to show the benefit of a newtreatment, even though it has some benefit). There is a trade-off between error rates--lower alpha will increase beta.14.Why is "Ho: "M1= M2" not a proper null hypothesis? SolutionThe null hypothesis to be formulated should state that there is NO significant differencebetween M1 and M2
Report on Experiment Test Hypothesis_5
15.An experimenter expects an effect to come out in a certain direction. Is this sufficientbasis for using a one-tailed test? Why or why not? SolutionNot really. We need not to care about effects in the opposite direction. Just because wethink something will go one way or another is different.16.How do the Type I and Type II error rates of one-tailed and two-tailed tests differ? SolutionOne-tailedtests have lowerType II error ratesand more power than do two-tailedtests17.A two-tailed probability is .03. What is the one-tailed probability if the effect were in thespecified direction? What would it be if the effect were in the other direction? SolutionThe one-tailed probability if the effect were in the specified direction would be 0.015.The probability would however be 0.985 if the effect were in the other direction. 18.You choose an alpha level of .01 and then analyze your data. (a)What is the probability that you will make a Type I error given that thenull hypothesis is true? Solution
Report on Experiment Test Hypothesis_6
The probability of type I error is actually alpha given that the nullhypothesis is true so it is .01(b)What is the probability that you will make a Type I error given that thenull hypothesis is false? SolutionWhen null hypothesis is false, it is impossible to make a type I error. Itmeans probability that you will make a type I error given the nullhypothesis is false is zero19.Why doesn't it make sense to test the hypothesis that the sample mean is 42? SolutionHypothesis tests must be about parameters, not sample statistics20.True/false: It is easier to reject the null hypothesis if the researcher uses a smalleralpha) level. SolutionFalse21.True/false: You are more likely to make a Type I error when using a small sample thanwhen using a large sample. Solution
Report on Experiment Test Hypothesis_7
False22.True/false: You accept the alternative hypothesis when you reject the null hypothesis. SolutionTrue23.True/false: You do not accept the null hypothesis when you fail to reject it. SolutionFalse 24.True/false: A researcher risks making a Type I error any time the null hypothesis isrejected. SolutionTrue
Report on Experiment Test Hypothesis_8

End of preview

Want to access all the pages? Upload your documents or become a member.

Related Documents
Applied Statistical Methods | Assignment | Answers
|6
|471
|22