week_10_S2_Review

week_10_S2_Review - Statistics 10: Week ten session two...

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Unformatted text preview: Statistics 10: Week ten session two Review Conducted Based on Quiz six Results (chapters 119-21) Questions missed by 45%-55% on the quiz and similar concepts will be discussed in Review Jenny asks a random sample of 200 UCLA students and asks them if they watch CNN. Of the 200, 120 respond "yes". She reports the following data: A = (0.60) B = (0.60 +/— l.96*0.035) What is the best answer? Choose one answer. a. A is a point estimate of a sample and B is a confidence interval for a sample. b. A is a statistic and B is an interval estimate of a parameter. c. A is a point estimate of a parameter and B is an interval estimate of a statistic. d. A is a parameter and B is an interval estimate of a sample. Missing concept: Point estimate and interval estimate Question 5 The Z value found for testing the null that P = 0.60 against the null that P# 0.60 is calculated to be 4.3. What is the best answer? Choose one answer. a. We need the alpha level to decide whether we should reject the null 0t not. b. There is strong evidence against the null hypothesis and we should reject it. c. Given the large Z value confidence level is quite high and we should not reject the null. d. Given that the Z value is high, the power of the test should be high, and so we should not reject the null. Missing concept: Decision about null based on Z value Question six What would be an alternative way of stating the following hypothesis? We expect 50% of the American public to endorse proposition X. Choose one answer. a. We expect the majority of American public to be pro proposition X. b. We expect the majority of American public to be against proposition X. c. We expect the American public to be indifferent about proposition X. d. We need to have the level of significance in order to answer this question. Missing concept: Translating hypotheses stated in symbols to words Question 7 A polling agency makes the following report: We are 95% confident that the percentage of American people who endorse the president's economic package is between 60% to 70%. What is the best answer? Choose one answer. a. This confidence interval is about P. b. This confidence interval is about P1 — P2 c. This confidence interval is about pA . d. This confidence interval is about p/‘l — p"2. e. This confidence interval is about Mue. Missing concept: Confidence intervals are about parameters and not statistics Question 9. Martha wants to estimate the proportion of UCLA students who prefer power points as a mean of presenting the lectures by the professor. For a random sample of 250 UCLA students. 55% say that they prefer power points. She then proceeds to calculate the 90% confidence interval. What is the best answer? Choose one answer. a. The 90% confidence interval relates to the truth about how all of UCLA students feel about using power points in the lecture. b. The 90% confidence interval refers to the truth about the sample statistics or the 55% that Martha found. c. The 90% confidence interval shows that if Martha took 100 random samples of the size 250 from UCLA students, in 90 out f 100 cases the she would find p" to be 0.55. d. The 90% confidence interval relates to the sample statistic and it is a point estimate of the population parameter. Missing concept: Generalization of confidence interval results to the population from which the random sample was drawn Question 17: A physics professor has observed that for several years 15% of the students who initially enroll for introductory physics drop the course before the quarter ends. A educational company has suggested to him that if he tires a series of films and videos about the major concepts in physics the students will get involved and the drop rate would go down. He decides to give it a shot and try their material for one quarter. If the null hypothesis is that the films and videos would not cause the drop out rate to go down, what would be a type 11 error. Choose one answer. a. If the drop out rate did not go down, and he still used them films and videos, he would be making a type ll error. b. If the drop out rate went down, and he used the films and videos, he would be making a type II error. e. If the drop out rate did not go down, and he used the films and the videoes, he would be making a type I] error. d. If the drop out rate went down, and he did not use the films and the videos, he would be making a type II error. Missing concept: Type 11 error and power of the test Question 25: A researcher wants to find out whether in the legal field there is any relationship between gender and annual income. For a random sample of male and female attorneys, who graduated from the same school over he the last 20 years, he finds the P value to be .03. He wants to set his level of confidence equal to 99%, what is the best answer. Choose one answer. a. He should conclude that there is a relationship between gender of the attorney and annual income because the actual risk of rejecting the true null is less than the risk he is willing to take to reject a true null. b. He should conclude that there is no relationship between gender of the attorney and annual income because the actual risk of rejecting the true null is more than the risk he is willing to take to reject a true null. c. He should conclude that there is no relationship between gender of the attorney and annual income because the actual risk of rejecting the true null is less than the risk he is willing to take to reject a true null. d. He should conclude that there is a relationship between gender of the attorney and annual income because the actual risk of rejecting the true null is less than the risk he is willing to take to reject a true null. Deciding about null H0: ul - [1.2 = 0 based on P value Question 27: On a statistics exam, the students are asked to test the null that a coin is fair. They are required to do this via the calculation of the P value and the 95% confidence interval and cross check their results. They are asked to set alpha = 0.05 Sam calculates the P value to be 0.02 and he rejects the null. He also calculates the confidence interval to be from 0.45 to 0.55. He uses Z = :/—1.96 How would you grade Sam's paper? Choose one answer. a. Sam should get full credit because his P value is less than 0.05 and is rejecting the null. b. Sam should be given partial credit because he found the coin to be fair. c. Sam should not be given any credit because he findings are contradictory. d. Sam should be given full credit because he calculated both the P value and the confidence interval. Missing Concept: Confidence interval and P value should give you the same results regarding rejection of H0 Question 30: John is testing the null hypothesis that gender does not have any effect on political affiliation. He tests the null and he finds the P value to be 0.32. What is the meaning of 0.32? The level of confidence is equal to 0.05. Choose one answer. a. Given that P is more than 0.05, he should fail to reject the null, and if he does reject it, his risk is 95%. b. Given that P is more than 0.05, he should fail to reject the null, and if he does reject it, his risk is 32%. c, Given that P is more than 0.05, he should fail to reject the null, and if he does reject it, his risk is 5%. d. Given that P is more than 0.05, he should fail to reject the null, and if he does reject it, his risk is 68%. Missing concept: Meaning of P value and type I error (alpha) Question 31 The null hypothesis is that the average annual income in a certain country is $25,000.00 Linda is wondering whether the annual income of the people living in his suburb is higher than the overall population. Thus, she takes a random sample of 121 families from her suburb and computes the 95% confidence of annual income and finds it to be: $22 ,000300 to 28 ,000:00 Given that she did not make any calculation error in the computation of the confidence interval, what is the best answer. Choose one answer. a. She should find the P value to be less than 0.05 and she should not reject the null. b. She should not have calculated the confidence interval for the mean; instead she should have calculated the confidence interval for the proportion. 0. Her sample size is not large enough to decide about rejecting or not rejecting the null; she needs a larger sample. d. She should find the P value to be more than 0.05 and she should not reject the null. Missing concept: Making conclusions about null based on the confidence interval Question 37: Suppose that you are testing the following null: HO: Mue 1 - Mue 2 = 0 After you carry out the relevant calculations, you find Z = 1.76. Given that n1 = n2 = 200, and given that you set alpha equal to 0.05, what is the best answer? Choose one answer. a. You reject the null hypothesis for a one—tailed test and fail to reject it for a two-tailed test. b. You fail to reject the null hypothesis for both a one—tailed and a two—tailed test. c. You reject the null hypothesis for both a one—tailed and a two—tailed tests. (1. You reject the null hypothesis for a two—tailed test and fail to reject it for a one—tailed test. Missing concept again: Conclusion about null based on Z value APPENDIX D Tables and Selected Formulas A-95 Table Z Second decimal place in z Areasunderthe 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 standard Normal curve 0.0001 0.0001 0.0001 0.0001. 0.0001 0.0001 0.0001 0.0001 . 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 — 3. 7 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 — 3. 6 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 — 3.5 0.0002 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 ‘ 0.0003 0.0003 0.0003 ~34 0.0003 0.0004 0.0004 0.0004 0.0004 0.0004 0.0004 0.0005 0.0005 0.0005 ~33 0.0005 0.0005 0.0005 0.0006 0.0006 0.0006 0.0006 0.0006 0.0007 0.0007 - 3.2 0.0007 0.0007 0.0008 0.0008 0.0008 0.0008 0.0009 0.0009 0.0009 0.0010 0.0010 0.0010 0.0011 0.0011 0.0011 0.0012 0.0012 0.0013 0.0013 0.0013 0.0014 0.0014 0.0015 0.0015 0.0016 0.0016 0.0017 0.0018 0.0018 0.0019 0.0019 0.0020 0.0021 0.0021 0.0022 0.0023 0.0023 0.0024 0.0025 0.0026 0.0026 0.0027 0.0028 0.0029 0.0030 0.0031 0.0032 0.0033 0.0034 0.0035 0.0036 0.0037 0.0038 0.0039 0.0040 0.0041 0.0043 0.0044 0.0045 0.0047 0.0048 0.0049 0.0051 0.0052 0.0054 0.0055 0.0057 0.0059 0.0060 0.0062 0.0064 0.0066 0.0068 0.0069 0.0071 0.0073 0.0075 0.0078 0.0080 0.0082 0.0084 0.0087 0.0089 0.0091 0.0094 0.0096 0.0099 0.0102 0.0104 0.0107 0.0110 0.0113 0.0116 0.0119 0.0122 0.0125 0.0129 0.0132 0.0136 0.0139 0.0143 0.0146 0.0150 0.0154 0.0158 0.0162 0.0166 0.0170 0.0174 0.0179 0.0183 0.0188 0.0192 0.0197 0.0202 0.0207 0.0212 0.0217 0.0222 0.0228 0.0233 0.0239 0.0244 0.0250 0.0256 0.0262 0.0268 0.0274 0.0281 0.0287 0.0294 0.0301 0.0307 0.0314 0.0322 0.0329 0.0336 0.0344 0.0351 0.0359 0.0367 0.0375 0.0384 0.0392 0.0401 0.0409 0.0418 0.0427 0.0436 0.0446 0.0455 0.0465 0.0475 0.0485 0.0495 0.0505 0.0516 0.0526 0.0537 0.0548 0.0559 0.0571 0.0582 0.0594 0.0606 0.0618 0.0630 0.0643 0.0655 0.0668 0.0681 0.0694 0.0708 0.0721 0.0735 0.0749 0.0764 0.0778 0.0793 0.0808 0.0823 0.0838 0.0853 0.0869 0.0885 0.0901 0.0918 0.0934 0.0951 0.0968 0.0985 0 0.1020 0.1038 0.1056 0.1075 0.1093 0.1112 0.1131 0.1151 0.1170 0.1190 0.1210 0.1230 0.1251 0.1271 0.1292 0.1314 0.1335 0.1357 0.1379 0.1401 0.1423 0.1446 0.1469 0.1492 0.1515 0.1539 0.1562 0.1587 0.1611 0.1635 0.1660 0.1685 0.1711 0.1736 0.1762 0.1788 0.1814 0.1841 0.1867 0.1894 0.1922 0.1949 0.1977 0.2005 0.2033 0.2061 0.2090 0.2119 0.2148 0.2177 0.2206 0.2236 0.2266 0.2296 0.2327 0.2358 0.2389 0.2420 0.2451 0.2483 0.2514 0.2546 0.2578 0.2611 0.2643 0.2676 0.2709 0.2743 0.2776 0.2810 0.2843 0.2877 0.2912 0.2946 0.2981 0.3015 0.3050 0.3085 0.3121 0.3156 0.3192 0.3228 0.3264 0.3300 0.3336 0.3372 0.3409 0.3446 0.3483 0.3520 0.3557 0.3594 0.3632 0.3669 0.3707 0.3745 0.3783 0.3821 0.3859 0.3897 0.3936 0.3974 0.4013 0.4052 0.4090 0.4129 0.4168 0.4207 0.4247 0.4286 0.4325 0.4364 0.4404 0.4443 0.4483 0.4522 0.4562 0.4602 0.4641 0.4681 0.4721 0.4761 0.4801 0.4840 0.4880 0.4920 0.4960 0.5000 TM 2 S —3.90, the areas are 00000 to four decimal places. —0.0 ...
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This note was uploaded on 12/03/2011 for the course STATISTICS 10 taught by Professor Gould during the Fall '11 term at UCLA.

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week_10_S2_Review - Statistics 10: Week ten session two...

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