Atividade - Statistics 4 UNP

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Pergunta 1
0 em 1 pontos
	
	
	
	A recent Gallup poll concerning abortion reported that 30% (.30) of the sampled U.S. adults said that abortion should be legal in all cases. The report added that the margin of error at the 95% confidence level was 4% (.04).
Skill: Calculate interpret the confidence interval for the population proportion p, and recognize the effect of level of confidence and sample size on the precision of the interval estimation.
"multiple choice" question: select the correct answer. Which of the following is the correct interpretation of the margin of error in this case? 
	
	
	
	
		Resposta Selecionada:
	 
We are 95% confident that the proportion of all U.S. adults who feel that abortion should be legal in all cases is more than .04 away from .30. 
	Resposta Correta:
	 
 We are 95% confident that the proportion of all U.S. adults who feel that abortion should be legal in all cases is no more than .04 away from .30. 
	
	
	
Pergunta 2
1 em 1 pontos
	
	
	
	Skill: Carry out the ANOVA procedure or comparing more than two population means.
"multiple choice" question: select the correct answer. Consider the following situation when comparing three populations’ means:
and testing:
H0: μ1 = μ2 = μ3
Ha: Not all the μ’s are equal
Consider now the following two scenarios of what the three samples might look like. Note that both scenarios have the same three sample means:
Scenario 1: 
Scenario 2: 
In which of the two scenarios is the ANOVA F-test statistic larger (providing more evidence to reject H0)? 
	
	
	
	
		Resposta Selecionada:
	 
Scenario 2, since the variability within groups (i.e., the variability in the samples) is much smaller than the variability within groups in Scenario 1.
	Resposta Correta:
	 
Scenario 2, since the variability within groups (i.e., the variability in the samples) is much smaller than the variability within groups in Scenario 1.
	Feedback da resposta:
	This is correct. The F-test statistic in Scenario 2 will be larger since the variability within groups (which is in the denominator of the F-test statistic) is much smaller.
	
	
	
Pergunta 3
1 em 1 pontos
	
	
	
	Skill: Carry out the chi-square test for the independence of two categorical variables and draw meaningful conclusions.
"multiple choice" question: select the correct answer. When the Chi-square test for independence is carried out, the researchers find that the P-value of the test is 0.01. Which of the following is the appropriate conclusion at the 0.05 significance level?
	
	
	
	
		Resposta Selecionada:
	 
The data provided enough evidence to conclude that birth order and delinquent behavior are independent.
	Resposta Correta:
	 
The data provided enough evidence to conclude that birth order and delinquent behavior are independent.
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 4
1 em 1 pontos
	
	
	
	Skill: Recognize the different steps of hypothesis testing and its logic. In particular, determine the hypotheses, interpret the p-value and draw conclusions.
"multiple choice" question: select the correct answer. Suppose that the p-value of a test is 0.035. Which of the following is correct regarding the conclusions we can draw?
	
	
	
	
		Resposta Selecionada:
	 
We can reject the null hypothesis at a significance level of 0.05 but cannot reject the null hypothesis at a significance level of 0.01
	Resposta Correta:
	 
We can reject the null hypothesis at a significance level of 0.05 but cannot reject the null hypothesis at a significance level of 0.01
	Feedback da resposta:
	This is correct. We can reject the null hypothesis when the p-value is smaller than the significance level. Therefore, if p-value=0.035, we can reject the null hypothesis at a significance level of 0.05 but cannot reject the null hypothesis at a significance level of 0.01.
	
	
	
Pergunta 5
1 em 1 pontos
	
	
	
	Skill: Carry out the two-sample t-test for comparing two population means when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. 70 pre-school children, were each randomly assigned to be taught by either Method 1 or Method 2. The outcome (the response) is a performance measure of the motor skill (higher is better) as measured by an outside expert who did not know which teaching method each child was assigned to. Here are the summary statistics of performance measure data:
Which of the following justifies why we can safely use the two-sample t-test in this case?
	
	
	
	
		Resposta Selecionada:
	 
The two samples are independent (since each of the children was randomized to one of the two methods) and both samples sizes are larger than 30.
	Resposta Correta:
	 
The two samples are independent (since each of the children was randomized to one of the two methods) and both samples sizes are larger than 30.
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 6
1 em 1 pontos
	
	
	
	Skill: Recognize the different steps of hypothesis testing and its logic. In particular, determine the hypotheses, interpret the p-value and draw conclusions.
"multiple choice" question: select the correct answer. Which of the following is true in hypothesis testing?
	
	
	
	
		Resposta Selecionada:
	 
The smaller the p-value, the more evidence the data provide against the null hypothesis and in favor of the alternative hypothesis. 
	Resposta Correta:
	 
The smaller the p-value, the more evidence the data provide against the null hypothesis and in favor of the alternative hypothesis. 
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 7
1 em 1 pontos
	
	
	
	In 1989, a major earthquake struck the San Francisco Bay area. The earthquake caused major damage, and would be expected to have emotional post-traumatic stress effects on the residents. Any psychological measure taken in the days or weeks just before the quake would have provided a good baseline for subsequent comparison.Two Stanford researchers happened to measure the depression level of 25 college students from the San Francisco Bay area two weeks before the quake. They then measured depression for the same group of 25 students again 10 days after the earthquake to track the students’ adjustment to the traumatic event. The depression scale that the researchers used is such that the higher the score the more depressed the individual is. Do the data provide evidence that students in the San Francisco Bay area became more depressed following the earthquake?
Let [Math Processing Error] be the mean difference in depression score (Before earthquake – After earthquake) of all students in the San Francisco Bay area.
Skill: Carry out the paired t-test when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. Which of the following are the appropriate null and alternative hypotheses?
	
	
	
	
		Resposta Selecionada:
	 
H0: μd = 0
Ha: μd < 0
	Resposta Correta:
	 
H0: μd = 0
Ha: μd < 0
	Feedback da resposta:
	This is correct. If students became more depressed after the earthquake, we expect the differences (depression before – depression after) to be, on average, negative.
	
	
	
Pergunta 8
1 em 1 pontos
	
	
	
	Skill: Calculate interpret the confidence interval for the population proportion p, and recognize the effect of level of confidence and sample size on the precision of the interval estimation.
"multiple choice" question: select the correct answer. We can safely construct the confidence interval for the population proportion using the data from this random sample because: 
	
	
	
	
		Resposta Selecionada:
	 
the sample size n=700 is much larger than 30.
	Resposta Correta:
	 
the sample size n=700 is much larger than 30.
	Feedback da resposta:
	This is correct.Pergunta 9
1 em 1 pontos
	
	
	
	Skill: Carry out the two-sample t-test for comparing two population means when appropriate and draw meaningful conclusions.
"multiple choice" question: select the correct answer. 
The data analysis also found that the 95% confidence interval for μ1 − μ2  is (1.1, 6.1).Which of the following is the correct interpretation of this interval? 
	
	
	
	
		Resposta Selecionada:
	 
We are 95% confident that the mean performance score of all children taught by Method 1 is between 1.1 and 6.1 points higher than the mean performance score of all children taught by Method 2.
	Resposta Correta:
	 
We are 95% confident that the mean performance score of all children taught by Method 1 is between 1.1 and 6.1 points higher than the mean performance score of all children taught by Method 2.
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 10
1 em 1 pontos
	
	
	
	Skill: Perform inference for the linear relationship between two quantitative variables
"multiple choice" question: select the correct answer. Since the data displayed a linear relationship, the correlation coefficient was calculated and was found to be r=−0.81. Based on the scatterplot and the value of the correlation coefficient, it would make sense to test the significance of this observed linear relationship between IQ and DI. The appropriate hypotheses are: 
	
	
	
	
		Resposta Selecionada:
	 
H0: IQ and DI are not linearly relatedHa: IQ and DI are linearly related.
	Resposta Correta:
	 
H0: IQ and DI are not linearly relatedHa: IQ and DI are linearly related.
	Feedback da resposta:
	This is correct.