Question 1

A cell in a bivariate correlation matrix shows a value of 1 for the 'R' statistic. How would you interpret this value?
A) positive correlation present
B) one case with both variable values
C) incorrect p value in the table
D) correlation of a variable with itself

Accepted Answer

A correlation of 1 in a bivariate correlation matrix indicates a perfect correlation, which typically occurs when a variable is correlated with itself.

Question 2

What is the statistical measure generally shown in a cross-tabulation between two categorical variables? A) R² B) R C) ⁫⁫⁫⁫ᵪ² D) variance

Accepted Answer

The correct statistical measure generally shown in a cross-tabulation between two categorical variables is the Chi-square (χ²) statistic, which is represented by option C. This measure is used to determine if there is a significant association between the two variables.

Question 3

What is a multichotomous variable?
A) a numeric variable with multiple decimals
B) a categorical variable with one or more categories
C) an interval variable with one or more values
D) a categorical variable with two or more categories

Accepted Answer

A multichotomous variable is a type of categorical variable that can take on two or more categories, unlike a dichotomous variable which is limited to two categories.

Question 4

Which measure is used to analyze difference in means in an ANOVA test? A) R² B) F statistic C) standard deviation D) ᵪ²

Accepted Answer

The F statistic is used in ANOVA (Analysis of Variance) tests to analyze the differences between group means and to assess the significance of those differences.

Question 5

"Statistical uncertainty" means a sample estimate can never be exactly equal to the population parameter.

Accepted Answer

Statistical uncertainty acknowledges that there is a margin of error in sample estimates, but it does not imply that a sample estimate can never be exactly equal to the population parameter; it's just unlikely.

Question 6

Inferential statistics means reaching a conclusion about characteristics of a population based on sample data.

Accepted Answer

Inferential statistics involves using sample data to make generalizations or predictions about a population.

Question 7

A "point estimate" is a summary statistic, such as the mean or proportion, of the population.

Accepted Answer

A "point estimate" is a summary statistic that comes from a sample and is used to estimate the corresponding population parameter, not the population itself.

Question 8

The mean income of residents of Long Island City, NY, was $32,500. The mean income of a random sample of 200 residents of Long Island City was found to be $28,900. The difference between the two numbers ($3,600) is known as sampling error.

Accepted Answer

Sampling error refers to the difference between a population parameter (in this case, the mean income of all residents of Long Island City, NY) and a statistic (the mean income of a random sample of 200 residents). The $3,600 difference represents the discrepancy between the actual mean income and the mean income estimated from the sample.

Question 9

The higher the precision of a sample estimate, the lower is its sampling error.

Accepted Answer

Precision refers to the closeness of the estimates to each other (i.e., how repeatable the results are), and higher precision typically indicates lower variability among the estimates. Lower variability (or higher precision) in the estimates suggests that the sampling error, which is the difference between the sample estimate and the true population parameter, is smaller.

Question 10

The standard error is an estimate of the sampling error of a point estimate.

Accepted Answer

The answer of The standard error is an estimate of...

Question 11

The sample size drawn from a population was increased from 200 cases to 1,000 cases. This increase in sample size reduced the standard error of summary statistics calculated from the independent variable in the data.

Accepted Answer

Increasing the sample size from 200 to 1,000 cases reduces the standard error of summary statistics because the standard error decreases as the square root of the sample size increases, leading to more precise estimates of the population parameters.

Question 12

Choosing a higher confidence level results in a smaller range for margin of error of a sampling estimate.

Accepted Answer

Choosing a higher confidence level actually results in a wider range for the margin of error because it means you want to be more certain that the true parameter falls within your interval, which requires expanding the interval.

Question 13

A confidence level of 99% is interpreted as the difference between a sample estimate and the population parameter is less than the margin of error 99% of the time.

Accepted Answer

A confidence level of 99% means that there is a 99% probability that the true population parameter is within the margin of error of the sample estimate.

Question 14

A confidence interval is calculated as Point Estimate (+/-) 2*Margin of Error.

Accepted Answer

A confidence interval is typically calculated as Point Estimate (+/-) Margin of Error, where the Margin of Error includes the critical value (which may not always be 2) times the standard error of the estimate. The "2" is specific to a 95% confidence level assuming a normal distribution, but other confidence levels use different critical values.

Question 15

What are the limits, if any, to values of uncertainty measures such as standard error, confidence level, and confidence interval?

Accepted Answer

The answer of What are the limits, if any, to...

Question 16

Distinguish between random error and bias. Illustrate the differences with the help of an example.

Accepted Answer

The answer of Distinguish between random error and bias. Illustrate...

Question 17

Describe the steps in developing a hypothesis test. Walk through these steps with an example.

Accepted Answer

The answer of Describe the steps in developing a hypothesis...

Question 18

Write a hypothesis statement on cigarette smoking and the probability of cancer as the variables of interest. You may have 2 statements for the null and the alternative hypothesis respectively.

Accepted Answer

The answer of Write a hypothesis statement on cigarette smoking...

Question 19

Explain what is a p value, and how it is used in hypothesis testing. Provide an example.

Accepted Answer

The answer of Explain what is a p value, and...

Question 20

In a hypothesis test, a significance level of 0.05 was chosen. How would you interpret this value?

Accepted Answer

The answer of In a hypothesis test, a significance level...

Quiz 13: Uncertainty of Numeric Estimates

A cell in a bivariate correlation matrix shows a value of 1 for the 'R' statistic. How would you interpret this value?

What is the statistical measure generally shown in a cross-tabulation between two categorical variables?

What is a multichotomous variable?

Which measure is used to analyze difference in means in an ANOVA test?