Test 3

If, for a sample in which the subjects are randomly chosen, the mean income is $45,000, the sample size is 1600, the standard deviation of the sample is $4,000, and the standard error of the mean is $100, what, approximately, is the 95% confidence interval for the population mean? Recall that .

$44,800 to $45,200.

If, for a sample in which the subjects are randomly chosen, the mean income is $1,000, the sample size is 100, the standard deviation of the sample is $100, and the standard error of the mean is $10, what, approximately, is the 99.7% confidence interval for the population mean? Recall that .

$970 to $1,030.

If a mean age of a sample of 100 randomly chosen individuals is 48 and the standard deviation of the sample is 16, what is the standard error of the mean? Recall that

1.6

How large, in %, is the area to the left of -1 (standard errors)?

16%

If the expected numbers in the cells [A, B, C, D] in the second table were [50, 50, 50, 50], then what would ∑ be?

32

6. How large, in %, is the area to the left of 2 (standard errors)?

97.5%

Which of the following is not true about a sampling distribution?

A sampling distribution represents a HYPOTHETICAL distribution, showing what the true population distribution would look like if our sample size were infinitely large.

Which type of sample is likely to be most useful for the process of statistical inference?

A small, randomly collected sample.

Which of the following is not true about normal distributions?

As the name implies, they are quite common in everyday experience.

What is the key insight of the Central Limit Theorem?

Regardless of the shape of a frequency distribution of a RANDOMLY chosen sample, a hypothetical distribution of an infinite number of sample means will be normally distributed, with a knowable variance.

For a Tabular Analysis with 2 categories for the independent variable and 3 categories for the dependent variable the researcher computes . . The degree of freedom for the statistical test is given by . Which of the following is true regarding rejection of the null hypothesis?

The null is rejected at the 10% significance level.

Which of the following accurately describes a difference of means test?

This is a test that is used when we want to test whether the value of a CONTINUOUS dependent variable is different across values of a CATEGORICAL independent variable

The process of statistical inference is defined as

Trying to learn about a characteristic about a broader population based on observations of only a sample from that population.

Suppose a reputable pollster reports that, on the basis of a random sample of American adults, the President's approval rating is 50%, and that the margin of error is plus or minus 4%. What is the correct interpretation of this reported result?

We can be approximately 95% confident that the true level of approval in the population as a whole is somewhere between 46% and 54%.

Which of the following accurately describes a p‐value? (2nd)

Both (a) and (b) are correct.

Which of the following is generally not an essential component of the process of statistical inference?

Data for the entire population.

Which of the following accurately describes a p‐value? (1st)

However small, a p‐value cannot be exactly equal to zero.

For a Difference of Means Analysis with 2 categories for the independent variable and observations in the first category and observations in the second category, the researcher computes . . The degree of freedom for the statistical test is given by . Which of the following is true regarding the researcher's decision based on a 5% significance level?

In the appropriate critical value table she uses the row for a degree of freedom of 80 and rejects the null hypothesis.

A relationship between two variables is described as "statistically significant" under which of the following circumstances?

Neither (a) nor (b) are correct

The value of a Chi‐squared statistic calculated for this table is 37.89 with a corresponding p‐value below 0.001. Based on this information, what can we say about the relationship between these two variables?

None of the above

Which of the following accurately describe the expected numbers [A, B, C, D] in the second table?

None of the above.

Which of the following accurately describe correlation coefficients?

all the above

Which of the following accurately describes the relationship between a covariance and a correlation coefficient for the same two variables?

if the covariance between two variables is POSITIVE the correlation coefficient between the same two variables will also be POSITIVE

For an analysis of a Correlation Coefficient the researcher computes a Pearson's . and . , where . The degree of freedom for the statistical test is given by . Which of the following is true regarding the researcher's decision based on a 5% significance level?

in the appropriate critical value table she uses the row for a degree of freedom of 20 and rejects the null hypothesis.

Judging from this table, what is the relationship between Iraq War approval and vote in the 2005 U.K. parliamentary elections?

it would appear that people who approved of Britain's involvement in Iraq were more likely to vote for the Labour Party than those who DID NOT approve.