Stats Homework # – Flashcards
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Exhibit 17-2 Consider the following time series. t 1 2 3 4 Yi 4 7 9 10 Refer to Exhibit 17-2. The forecast for period 10 is
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22.5
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The time series component that reflects variability due to natural disasters is called
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irregular
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Given an actual demand of 61, forecast of 58, and an mc002-1.jpg of .3, what would the forecast for the next period be using simple exponential smoothing?
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58.9
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A group of observations measured at successive time intervals is known as
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a time series
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For the following time series, you are given the moving average forecast. The mean squared error equals
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41
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One measure of the accuracy of a forecasting model is
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the mean square error
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Exhibit 17-3 Consider the following time series. Refer to Exhibit 17-3. The forecast for period 10 is
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-6.7
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Exhibit 17-1 Below you are given the first five values of a quarterly time series. The multiplicative model is appropriate and a four-quarter moving average will be used. Refer to Exhibit 17-1. An estimate of the seasonal-irregular component for Quarter 3 of Year 1 is
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.64
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A component of the time series model that results in the multi-period above-trend and below-trend behavior of a time series is
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a cyclical component
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The following linear trend expression was estimated using a time series with 17 time periods. Tt = 129.2 + 3.8t The trend projection for time period 18 is
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197.6
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Below you are given the first two values of a time series. You are also given the first two values of the exponential smoothing forecast. If the smoothing constant equals .3, then the exponential smoothing forecast for time period three is
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19.2
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Exhibit 17-2 Consider the following time series. t 1 2 3 4 Yi 4 7 9 10 Refer to Exhibit 17-2. The intercept, b0, is
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2.5
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Exhibit 12-2 Last school year, the student body of a local university consisted of 30% freshmen, 24% sophomores, 26% juniors, and 20% seniors. A sample of 300 students taken from this year's student body showed the following number of students in each classification. Freshmen 83 Sophomores 68 Juniors 85 Seniors 64 We are interested in determining whether or not there has been a significant change in the classifications between the last school year and this school year. Refer to Exhibit 12-2. The expected number of freshmen is
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90
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Exhibit 12-5 The table below gives beverage preferences for random samples of teens and adults. We are asked to test for independence between age (i.e., adult and teen) and drink preferences. Refer to Exhibit 12-5. The p-value is
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less than 0.005
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Exhibit 12-7 You want to test whether or not the following sample of 30 observations follows a normal distribution. The mean of the sample equals 11.83, and the standard deviation equals 4.53. Refer to Exhibit 12-7. The p-value is
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greater than 0.1
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Exhibit 12-3 In order to determine whether or not a particular medication was effective in curing the common cold, one group of patients was given the medication, while another group received sugar pills. The results of the study are shown below. We are interested in determining whether or not the medication was effective in curing the common cold. Refer to Exhibit 12-3. The hypothesis is to be tested at the 5% level of significance. The critical value from the table equals
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3.84
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Exhibit 12-7 You want to test whether or not the following sample of 30 observations follows a normal distribution. The mean of the sample equals 11.83, and the standard deviation equals 4.53. Refer to Exhibit 12-7. The calculated value for the test statistic equals
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2
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Exhibit 12-3 In order to determine whether or not a particular medication was effective in curing the common cold, one group of patients was given the medication, while another group received sugar pills. The results of the study are shown below. We are interested in determining whether or not the medication was effective in curing the common cold. Refer to Exhibit 12-3. The expected frequency of those who received medication and were cured is
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48
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Exhibit 12-4 In the past, 35% of the students at ABC University were in the Business College, 35% of the students were in the Liberal Arts College, and 30% of the students were in the Education College. To see whether or not the proportions have changed, a sample of 300 students was taken. Ninety of the sample students are in the Business College, 120 are in the Liberal Arts College, and 90 are in the Education College. Refer to Exhibit 12-4. The conclusion of the test is that the
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proportions have not changed significantly
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Exhibit 12-4 In the past, 35% of the students at ABC University were in the Business College, 35% of the students were in the Liberal Arts College, and 30% of the students were in the Education College. To see whether or not the proportions have changed, a sample of 300 students was taken. Ninety of the sample students are in the Business College, 120 are in the Liberal Arts College, and 90 are in the Education College. Refer to Exhibit 12-4. The expected frequency for the Business College is
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105
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The number of degrees of freedom for the appropriate chi-square distribution in a test of independence is
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number of rows minus 1 times number of columns minus 1
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Exhibit 12-3 In order to determine whether or not a particular medication was effective in curing the common cold, one group of patients was given the medication, while another group received sugar pills. The results of the study are shown below. We are interested in determining whether or not the medication was effective in curing the common cold. Refer to Exhibit 12-3. The p-value is
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less than .005
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Exhibit 12-4 In the past, 35% of the students at ABC University were in the Business College, 35% of the students were in the Liberal Arts College, and 30% of the students were in the Education College. To see whether or not the proportions have changed, a sample of 300 students was taken. Ninety of the sample students are in the Business College, 120 are in the Liberal Arts College, and 90 are in the Education College. Refer to Exhibit 12-4. The hypothesis is to be tested at the 5% level of significance. The critical value from the table equals
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5.991
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The degrees of freedom for a contingency table with 6 rows and 3 columns is
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10
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The degrees of freedom for a contingency table with 12 rows and 12 columns is
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121
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Exhibit 12-3 In order to determine whether or not a particular medication was effective in curing the common cold, one group of patients was given the medication, while another group received sugar pills. The results of the study are shown below. We are interested in determining whether or not the medication was effective in curing the common cold. Refer to Exhibit 12-3. The number of degrees of freedom associated with this problem is
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1
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Exhibit 12-2 Last school year, the student body of a local university consisted of 30% freshmen, 24% sophomores, 26% juniors, and 20% seniors. A sample of 300 students taken from this year's student body showed the following number of students in each classification. Freshmen 83 Sophomores 68 Juniors 85 Seniors 64 We are interested in determining whether or not there has been a significant change in the classifications between the last school year and this school year. Refer to Exhibit 12-2. The p-value is
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greater than 0.1
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Exhibit 12-5 The table below gives beverage preferences for random samples of teens and adults. We are asked to test for independence between age (i.e., adult and teen) and drink preferences. Refer to Exhibit 12-5. The test statistic for this test of independence is
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62.5
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An important application of the chi-square distribution is
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All of these alternatives are correct.
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Exhibit 12-4 In the past, 35% of the students at ABC University were in the Business College, 35% of the students were in the Liberal Arts College, and 30% of the students were in the Education College. To see whether or not the proportions have changed, a sample of 300 students was taken. Ninety of the sample students are in the Business College, 120 are in the Liberal Arts College, and 90 are in the Education College. Refer to Exhibit 12-4. This problem is an example of a
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multinomial population
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Exhibit 18-1 Fifteen people were given two types of cereal, Brand X and Brand Y. Two people preferred Brand X and thirteen people preferred Brand Y. We want to determine whether or not customers prefer one brand over the other. Refer to Exhibit 18-1. To test the null hypothesis, the appropriate probability distribution to use is
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binomial
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The level of measurement that is simply a label for the purpose of identifying an item is
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nominal measurement
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Exhibit 18-3 It is believed that the median yearly income in a suburb of Atlanta is $70,000. A sample of 67 residents was taken. Thirty-eight had yearly incomes above $70,000, 26 had yearly incomes below $70,000, and 3 had yearly incomes equal to $70,000. The null hypothesis to be tested is H0: median = $70,000. Refer to Exhibit 18-3. The p-value for this test is
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0.1336
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Exhibit 18-7 Two faculty members ranked 12 candidates for scholarships. Calculate the Spearman rank-correlation coefficient and test it for significance. Use a .02 level of significance. Refer to Exhibit 18-7. The value of test-statistics for testing significance of rank-correlation is
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Z=2.88
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The level of measurement that allows for the rank ordering of data items is
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ordinal measurement
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Exhibit 18-1 Fifteen people were given two types of cereal, Brand X and Brand Y. Two people preferred Brand X and thirteen people preferred Brand Y. We want to determine whether or not customers prefer one brand over the other. Refer to Exhibit 18-1. The p-value for this test is
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0.0074
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The Spearman rank-correlation coefficient is
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a correlation measure based on rank-ordered data for two variables
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The scale of measurement that is used to rank order the observation for a variable is called the
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ordinal scale
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A nonparametric version of the Parametric analysis of variance test is the
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Kruskal-Wallis Test
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Exhibit 18-6 Forty-one individuals from a sample of 60 indicated they oppose legalized abortion. We are interested in determining whether or not there is a significant difference between the proportions of opponents and proponents of legalized abortion. Refer to Exhibit 18-6. The conclusion is that there
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is a significant difference between the proportions
