23.8 is what needs answerd the other is just info for it please use the calculator method 4step23.8 Shrubs That Withstand Fire. Fire is a serious threat to shrubs in dry climates. Some shrubs can resprout from their roots after their tops are destroyed.SampleDe study of resprouting took place in a dry area of Mexico." The investigatorsAust clipped the tops of all the shrubs in the study. For the treatment, they thenortionapplied a propane torch to the stumps of the shrubs to simulate a fire, and forhe control, the stumps were left alone. The study included 24 shrubs, of which12 were randomly assigned to the treatment and the remaining 12 to the con-trol. A shrub is a success if it resprouts. For the shrub Xerospirea hartwegiana,all 12 shrubs in the control group resprouted, whereas only 8 in the treatmentgroup resprouted. How much does burning reduce the proportion of shrubs ofthis species that resprout? Give the 95% plus four confidence interval for theamount by which burning reduces the proportion of shrubs of this species thatresprout. The plus four method is particularly helpful when, as here, a count ofeither successes or failures is zero. Follow the four-step process as illustrated inExample 23.6 (page 540).A3D0.24070.0784CHARTER 23.6 Abecedarian Early Childhood EducationProgram: Adult OutcomesstepSTATE: The Abecedarian Project was a randomized controlled study to assesson several sociodemographic indicators. The project randomly assigned childrentreatment group, which was provided with early educational activities before keagarten, and the remainder to a control group. A recent follow-up study intervieedsubjects at age 30 and compared the college graduation rates (earning adegree).12 Here are the data for two groups:28.7 PearrelacesinfaninfantPopulationDescriptionneat pSampleSizeNumber ofSuccessesPopulationsumerSample ProportionTreatmentn, = 52Pi = 12/52 = 0.23081.12%3D%3DControln2 = 49P2 = 3/49% 3D 0.06122.How much does early childhood education increase the proportion earning a four-year degree by age 30?DA Cive a 90% confidence interval for the difference between populationproportions, p, - P2.(6) TH) GiSOLUE Tne conditions for the large-sample interval are not met because there areoniy 3 successes in the control group. However, we can use the plus four methodbecause the sample sizes for the treatment and the control group are both at least 5.Add four imaginary observations. The new data summary is23.8 ShrubPopulationDescriptionNumber ofPlus Four SampleProportionmates.PopulationSample SizeSuccessesOne str1Treatment n, + 2 = 54 12 + 1 = 13= 13/54 = 0.2407n + 2 = 51 3+1 = 4 2 = 4/51 = 0.0784%3D%3DControl%3D%3D2.The standard error based on the new facts istrol. Aal 12 sPi(1-P) P2(1- pa)SEp-P:n+ 2n2 + 2(0.2407)(0.7593)1 dnous(0.0784) (0.9216)unoueeither su5451=V0.00480 = 0.0693The plus four 90% confidence interval is(P-P2) ± z*SE, -p, = (0.2407 - 0.0784) (1.645) (0.0693)= 0.1623 0.1140CONCLUDE: We are 90% confident that the early childhood education prograincreases the proportion of high-risk children who earn a four-year degree by age30 by between 4.8% and 27.6%.=0.048 to 0.276APTER 2pter Sipe

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23.8 is what needs answerd the other is just info for it please use the calculator method 4step23.8 Shrubs That Withstand Fire. Fire is a serious threat to shrubs in dry climates. Some shrubs can resprout from their roots after their tops are destroyed.SampleDe study of resprouting took place in a dry area of Mexico.&#34; The investigatorsAust clipped the tops of all the shrubs in the study. For the treatment, they thenortionapplied a propane torch to the stumps of the shrubs to simulate a fire, and forhe control, the stumps were left alone. The study included 24 shrubs, of which12 were randomly assigned to the treatment and the remaining 12 to the con-trol. A shrub is a success if it resprouts. For the shrub Xerospirea hartwegiana,all 12 shrubs in the control group resprouted, whereas only 8 in the treatmentgroup resprouted. How much does burning reduce the proportion of shrubs ofthis species that resprout? Give the 95% plus four confidence interval for theamount by which burning reduces the proportion of shrubs of this species thatresprout. The plus four method is particularly helpful when, as here, a count ofeither successes or failures is zero. Follow the four-step process as illustrated inExample 23.6 (page 540).A3D0.24070.0784CHARTER 23.6 Abecedarian Early Childhood EducationProgram: Adult OutcomesstepSTATE: The Abecedarian Project was a randomized controlled study to assesson several sociodemographic indicators. The project randomly assigned childrentreatment group, which was provided with early educational activities before keagarten, and the remainder to a control group. A recent follow-up study intervieedsubjects at age 30 and compared the college graduation rates (earning adegree).12 Here are the data for two groups:28.7 PearrelacesinfaninfantPopulationDescriptionneat pSampleSizeNumber ofSuccessesPopulationsumerSample ProportionTreatmentn, = 52Pi = 12/52 = 0.23081.12%3D%3DControln2 = 49P2 = 3/49% 3D 0.06122.How much does early childhood education increase the proportion earning a four-year degree by age 30?DA Cive a 90% confidence interval for the difference between populationproportions, p, - P2.(6) TH) GiSOLUE Tne conditions for the large-sample interval are not met because there areoniy 3 successes in the control group. However, we can use the plus four methodbecause the sample sizes for the treatment and the control group are both at least 5.Add four imaginary observations. The new data summary is23.8 ShrubPopulationDescriptionNumber ofPlus Four SampleProportionmates.PopulationSample SizeSuccessesOne str1Treatment n, + 2 = 54 12 + 1 = 13= 13/54 = 0.2407n + 2 = 51 3+1 = 4 2 = 4/51 = 0.0784%3D%3DControl%3D%3D2.The standard error based on the new facts istrol. Aal 12 sPi(1-P) P2(1- pa)SEp-P:n+ 2n2 + 2(0.2407)(0.7593)1 dnous(0.0784) (0.9216)unoueeither su5451=V0.00480 = 0.0693The plus four 90% confidence interval is(P-P2) ± z*SE, -p, = (0.2407 - 0.0784) (1.645) (0.0693)= 0.1623 0.1140CONCLUDE: We are 90% confident that the early childhood education prograincreases the proportion of high-risk children who earn a four-year degree by age30 by between 4.8% and 27.6%.=0.048 to 0.276APTER 2pter Sipe

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