Question

1. A drug company is studying the effect of a new drug. In its clinical trials, the researcher used a significance level of .01. By using this significance level instead of the more usual .05, the researcher has

A) Expanded the critical region

B) Increased the critical value

C) Increased the probability of rejecting the Ho

2) When a researcher failed to reject the null hypothesis

A) The obtained statistical value is larger than the critical value

B) The obtained statistical value is smaller than the critical value  

C) Either a or b

3. A 95% confidence interval was calculated to be (15, 21). This means that if 100 such confidence intervals (CIs) were constructed then.

   A)95% of the CIs will be (15,21)

   B)95% of the CIs will include the population mean

   C)The population mean would lie between (15,21) 95 times.

   D)The population mean would be found in about 95 of the CIs

4. If you obtained a test score of 78 on a test with the average test score of your class is 70 and SD is 4, what proportion of scores are lower than yours? A)95% B)97.5% C)It cannot be determined from the information provided.

5. If you obtained a test score of 78 on a test with an average test score of your class is 70, and SD is 4. If your class have 36 students in total, what is the 95% CI range in estimate the test score of the population

1. [70-2.064*4, 70+2.064*4]

2. [72-2.064*4, 72+2.064*4]

3. [70-2.064*0.67, 70+2.064*0.67]

4. [72-2.064*0.67, 72+2.064*0.67]

6. A researcher found the correlation between IQ scores and reading ability is 0.78.

1. The people who have higher IQ scores also tend to have high reading ability

2. The people who have higher IQ scores are predicted to have a high reading ability.

3. Student A has a higher IQ score than student B, so student A will also have a higher reading ability than student B.

Question 3: True or False

	The correlation coefficient of 0.6 has a stronger association than a correlation coefficient of -0.6.
	The slope between X and Y has the same sign with the correlation coefficient of X and Y.
	The standard error is the standard deviation of the sampling distribution.
	The standard error with a sample size of 100 is larger than the standard error with a sample size of 50.
	Keeping other factors constant, the 95% CI has a broader range with sample size 100 than with a sample size of 50.
	Keeping other factors constant, the 95% CI has a broader range than the 99% CI.

Answer 1

1)

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µ =    70
σ =    4
  
P( X ≤    78)

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