PSC 310 Final

In this example, if an individual has judged that Iraq war is a complete failure, meaning that they have a value of 0 for the independent variable, what would be their expected value for "Blair Feelings?

(a) 0 (b) 5 ***(c) 4.7 (d) 0.31

For the next 3 questions, consider a variable with the following values for the seven observations in a data set: 35, 23, 28, 37, 23, 19, 31. What is the mean?

(a) 23. ***(b) 28. (c) 19. (d) None of the above. All of the numbers added together and divided by the amount of numbers

For the next 3 questions, consider a variable with the following values for the seven observations in a data set: 35, 23, 28, 37, 23, 19, 31. What is the median?

(a) 23. ***(b) 28. (c) 19. (d) None of the above. median is when you put the numbers in numerical order, it is the number in the middle or the 2 numbers in the middle divided by 2

Which of the following are useful for describing the values of a continuous variable?

(a) A box-whisker plot. (b) Rank statistics. (c) A kernel density plot. ***(d) All of the above.

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

(a) A clear conceptualization of what the underlying population is. (b) A representative sample. ***(c) Data for the entire population. (d) A predefined acceptable margin of error.

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

(a) A large sample of people who subscribe to a newspaper. (b) A large sample of students in an Introduction to American Politics course. (c) A large sample of people who responded to a pop-up ad inviting them to participate. ***(d) A small, randomly collected sample.

Which of the following accurately describes an ordinal variable?

(a) A one unit increase in the variable value always means the same thing. (b) Different values mean different things. (c) The categories are ordered from least to greatest. ***(d) Both b and c are accurate.

Which of the following accurately describes a continuous variable?

(a) A one-unit increase in the variable value always means the same thing. (b) Different values mean different things. ***(c) Both a and b are accurate. (d) Neither a nor b is accurate.

Which of the following accurately describes a categorical variable?

(a) A one-unit increase in the variable value always means the same thing. ***(b) Different values mean different things. (c) The categories are ordered from least to greatest. (d) Both b and c are accurate.

Which of the following accurately describes a p-value?

(a) A p=.01 means that there is a 1% chance that we would see the measured relationship due to random chance (b) For the same measured relationship, a larger sample size will lead to a smaller p-value. ***(c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

Which of the statements are accurate?

(a) By specifying a bivariate regression model we are assuming that the impact of a one unit increase in Xi will always be β. (b) By specifying a bivariate regression model we are assuming that there are no other variables that cause Yi. ***(c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

Which of the following statements are accurate?

(a) For every one-unit increase in "Blair Feelings", we can expect to see a 0.31 increase in "Iraq War Success Scale." ***(b) For every one-unit increase in "Iraq War Success Scale", we can expect to see a 0.31 increase in "Blair Feelings." (c) If the variable "Blair Feelings" is zero, it is highly likely that the variable "Iraq War Success Scale" will also be equal to zero. (d) None of the above.

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

(a) If the covariance between two variables is positive, the correlation coefficient between the same two variables will always be negative. ***(b) If the covariance between two variables is positive, the correlation coefficient between the same two variables will also be positive. (c) Regardless of the covariance between two variables, the correlation coefficient will always be positive. (d) None of the above.

The value of a chi-squared statistic calculated for this table is 37.89 with a corresponding p-value below .001. Based on this information, what can we say about the relationship between these two variables?

(a) It is highly likely that this relationship would occur due to random chance. (b) It is highly likely that there is a causal relationship between these two variables. (c) It is highly unlikely that there is a causal relationship between these two variables. ***(d) None of the above.

Which of the following is not true about normal distributions?

(a) It is the basis of statistical inference. ***(b) As the name implies, they are quite common in everyday experience. (c) Approximately 68% of the area under the curve lies within one standard deviation of its mean. (d) It is symmetrical about its mean.

Which of the following is true about the comparison between two randomly chosen samples, one with 1000 respondents, the other with 2000 respondents?

(a) Other things being equal, the larger sample will have a standard error one-half the size of the smaller sample. (b) Other things being equal, the larger sample will have wider confidence intervals than the smaller sample. ***(c) Adding still another 1000 respondents, to make the sample size 3000, would further shrink the standard error of the mean, but by a smaller amount than the difference between 1000 and 2000 respondents. (d) So long as both samples are randomly chosen, there is no meaningful difference between them.

Which of the following are useful for describing the values of a categorical variable?

(a) Rank statistics. (b) A kernel density plot. ***(c) A pie graph. (d) None of the above.

What is the key insight of the Central Limit Theorem, as discussed in Chapter 7 of the Kellstedt and Whitten text?

(a) Regardless of the shape of a frequency distribution, as the sample size gets larger and larger, that distribution will more closely resemble a normal distribution, and, when a sample hypothetically becomes infinitely large, it is guaranteed to be normally distributed. (b) For variables that are normally distributed, it is possible to use even a small sample to make inferences about the population. (c) For random samples, but only for random samples, the process of statistical inference does not depend on sample size. ***(d) 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.

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?

(a) Roughly half of the people who were invited to participate in the survey agreed to do so. (b) The true level of approval in the population is equal to 50%, with only a 4% chance that it is equal to something other than 50%. ***(c) We can be approximately 95% confident that the true level of approval in the population as a whole is somewhere between 46% and 54%. (d) We have not been given enough information to draw any solid interpretation of these facts.

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

(a) There does not appear to be any relationship whatsoever between these two variables. ***(b) It would appear that people who approved of Britain's involvement in Iraq were more likely to vote for Labour than those who did not approve of Britain's involvement in Iraq. (c) It would appear that people who do not approve of Britain's involvement in Iraq were more likely to vote for Labour than those who did not approve of Britain's involvement in Iraq. (d) There may be a relationship between these two variables, but from the way that this table has been set up it is impossible to figure out what is going on.

Which of the following statements are accurate about the population regression model?

(a) Ui, is the stochastic component of Yi. (b) â+BX, is the systematic component of Yi. ***(c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

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

(a) When there is a sufficiently high p-value. (b) When there is a credible causal claim about the relationship between the two variables. (c) Both (a) and (b) are correct. ***(d) Neither (a) nor (b) are correct.

Which of the following statements are accurate?

(a) With these results, if we know the value of "Iraq War Success Scale" then we will be able to predict the value of "Blair Feelings." Our predictions will on average be off by 2.4. (b) Even if an individual feels very negatively about how the Iraq war is going, they are quite unlikely to have the worst possible judgment about Tony Blair's competence. ***(c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

Which of the following statements are accurate?

(a) û, is an estimate of Ui (b) Xi is assumed to be measured without error. ***(c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

Check the Powerpoint for the discussion questions

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For the next 3 questions, consider a variable with the following values for the seven observations in a data set: 35, 23, 28, 37, 23, 19, 31. What is the mode?

***(a) 23. (b) 28. (c) 19. (d) None of the above. mean is the number that occurs the most in the data set

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

***(a) A sampling distribution represents a hypothetical distribution, showing what the true population distribution would look like if our sample size were infinitely large. (b) A sampling distribution for a variable is normally distributed even if the underlying population is not distributed normally for that variable. (c) Sampling distributions are almost never observed in real life. (d) The mean of a sampling distribution is equal to the true population mean.

Which of the following statements are accurate?

***(a) It is highly unlikely that we would see the relationship that we are seeing between the independent variable and the dependent variable in this model due to random chance. (b) This model explains about 90% of the variation in "Blair Feelings." (c) Both (a) and (b) are correct. (d) Neither (a) nor (b) are correct.

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

***(a) 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. (b) This is a test that is used when we want to test whether the value of a categorical dependent variable is different across values of a continuous independent variable. (c) This is a test that is used when we have two different continuous variables and we want to see if they have the same mean. (d) None of the above.

The process of statistical inference is defined as:

***(a) Trying to learn about a characteristic about a broader population based on observations of only a sample from that population. (b) Validating that the observed sample is indeed representative of the population as a whole. (c) Admitting that the researcher has not collected enough data to draw a conclusion. (d) Collecting data from the entire population of cases.

How many of the Z variables included in the model, does the multivariate regression model allow us to control for?

0

At around what n size does one begin to experience a diminishing return in terms of a reduction of margin of error for each additional case added

200 (?)

This regression assumption says that the population parameter for b for the relationship between X and Y does not vary

Linearity

What is the process of making probabilistic statements about a population characteristic based on our knowledge of a sample characteristic known as?

Statistical inference

In this form of bivariate analysis, we compare the observed frequencies with the frequencies we would expect if there were no relationship, to determine if a true relationship exists?

tabular analysis

In this form of bivariate analysis, we examine two continuous variables. We use a scatter plot to detect covariation and then calculate Pearson's r which ranges from 0.0 to 1.0 to determine the strength of association between the two continuous variables.

correlation coefficient

This is one of the more popular goodness-of-fit measures for the regression model. This particular version is used with the multivariate regression model and indicates the proportion of the variation in the dependent variable that is accounted for by the model

adjusted r squared

In this form of bivariate analysis, we examine a continuous dependent variable against a categorial independent variable to determine if the average values of the continuous variable are different according to the categories of the categorial variable

difference of means

According to probability theory, the sum of all possible outcomes must be

exactly 1

This regression mathematical requirement says that the number of cases must exceed the number of parameters to be estimated

n > k

A bell curve is also known as a

normal distribution

We can use this type of test when we are predicting a direction for our parameter estimate

one-tailed test

This is one of the more popular goodness-of-fit measures for the regression model. This particular versions is used with the bivariate regression model and indicates the proportion of the variation in the dependent variable that is accounted for by the model.

r squared

This is often referred to as the "rise=over-run" component of the line formula or b

slope

These are sometimes known as betas, they tell us the relative strength of a given variable by putting all of the variables onto a common metric so that we see how much Y changes for a one-unit increase in the standard deviation of X

standard regression coefficient

We can say a relationship exhibits this characteristic when the assumptions underlying the calculation of the p-value hold and the p-value is below the .05 threshold?

statistical significance

The u component of the population regression formula refers to this random or _________ component of the model.

stochastic

What ranges between 0 and 1 and is the probability that we would see the relationship we are finding because of random chance

the p value

In trying to draw the best line for a regression model, we typically look at the least squared values of each of the residuals for each line; however, we could also look at least ____________ of the residuals for each line

total value