BCTC STATS EXAM 1 EXAM REPORTED QUESTIONS WITH CORRECT DETAILED ANSWERS

BCTC STATS EXAM 1 EXAM REPORTED QUESTIONS WITH CORRECT DETAILED ANSWERS Why is a voluntary response sample generally unsuitable for methods of statistics? - Answer-People with special interests are more likely to respond, so the sample is likely to be biased. Based on a study of household incomes of men and women who are married, a researcher concludes that marriage causes people to become wealthier.Do you agree with this conclusion? - Answer-No. There may be a relationship between marital status and gross income, but that does not mean that one causes the other. Several studies showed that after drinking coffee, subjects had increased blood levels of antioxidants. Antioxidants have been associated with decreased risk of heart disease. A coffee company financed this research. What is wrong with this study? - Answer-self-interest study What is the goal of learning statistics? - Answer-To learn to distinguish between statistical conclusions that are likely to be valid and those that are seriously flawed Which of the following is NOT a misuse of statistics? - Answer-Utilizing valid statistical methods and correct sampling techniques Survey questions may be misleading if they are "loaded." To what does "loaded" refer? - Answer-Intentionally worded to elicit a desired response What is a self-interest study? - Answer-A survey in which the sponsor can enjoy monetary or other gains from the results Which of the following corresponds to the case when every sample of size n has the same chance of being chosen? - Answer-Simple random sample After constructing a relative frequency distribution summarizing IQ scores of college students, what should be the sum of the relative frequencies? - Answer-If percentages are used, the sum should be 100%. If proportions are used, the sum should be 1. _______ are sample values that lie very far away from the majority of the other sample values. - Answer-outliers A _______ helps us understand the nature of the distribution of a data set. - Answer-frequency distribution The population of ages at inauguration of all U.S. Presidents who had professions in the military is 62, 46, 68, 64, 57. Why does it not make sense to construct a histogram for this data set? - Answer-With a data set that is so small, the true nature of the distribution cannot be seen with a histogram. The bars in a histogram _______. - Answer-touch A histogram aids in analyzing the _______ of the data. - Answer-shape of the distribution A(n) _______ distribution has a "bell" shape. - Answer-normal A _______ is a plot of paired data (x,y) and is helpful in determining whether there is a relationship between the two variables. - Answer-scatterplot Which of the following is a common distortion that occurs in graphs? - Answer-Using a two-dimensional object to represent data that are one-dimensional in nature Why is it important to learn about bad graphs? - Answer-So that we can critically analyze a graph to determine whether it is misleading Methods used that summarize or describe characteristics of data are called _______ statistics. - Answer-descriptive A value at the center or middle of a data set is a(n) _______. - Answer-measure of center The systolic blood pressures of 40 women have a mean of 110.8 mm Hg and a standard deviation of 17.1 mm Hg. The highest systolic blood pressure measurement in this sample is 181 mm Hg. In this context, is a systolic blood pressure of 181 mm Hg "unusual"? Why or why not? - Answer-Yes, because it differs from the mean by more than two standard deviations. What is a voluntary response sample? - Answer-A sample in which the subjects themselves decide whether to be included in the study. Use common sense to determine whether the given event is either impossible, possible but very unlikely, or possible and likely. (New England beat Denver in a football game by a score of 140 to 100) - Answer-possible, but very unlikely In a study of a weight loss program, 45 subjects lost a mean of 2.7 lbs after 12 months. Methods of statistics can be used to show that if this diet had no effect, the likelihood of getting these results is roughly 6 chances in 1000. Does the weight loss program have statistical significance? Does the weight loss program have practical significance? - Answer-yes, because the results are unlikely to occur by chance Which of the following is typically the least important factor to consider when conducting a statistical analysis of data? - Answer-formula calculation What does it mean for the findings of a statistical analysis of data to be statistically significant? - Answer-The likelihood of getting these results by chance is very small. If we are collecting sample data for a study, the _______ that we choose can greatly influence the validity of our conclusions. For example, we can use sound statistical methods to analyze data in voluntary response samples, but the results are not necessarily valid. - Answer-sampling method How do a parameter and a statistic differ? - Answer-A parameter is a numerical measurement of a population; a statistic is a numerical measurement of a sample. Determine whether the value is from a discrete or continuous data set. (Time to learn a song is 4 hours) - Answer-continuous Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate. (Monthly rainfall: 2.4 in comma 2.6 in comma 2.8 in comma 3 in comma and 3.2 in) - Answer-ratio Some people responded to this request: "Dial 1-900-PRO-LIFE to participate in a telephone poll on abortion. ($3.95 per minute. Average call: 4 minutes You must be 16 years old.)" Identify the (a) sample and (b) population. Also, determine whether the sample is likely to be representative of the population. - Answer-sample: all people who responded population: individuals who were 16 years old Which of the following consists of discrete data? - Answer-number of suitcases on an airplane The Range Rule of Thumb roughly estimates the standard deviation of a data set as _______. - Answer-s = range/4 For data sets having a distribution that is approximately bell-shaped, _______ states that about 68% of all data values fall within one standard deviation from the mean. - Answer-the Empirical Rule