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1、英语测试作业参考答案1Identify the scales represented by the following kinds of data: Solution:Raw scores from a listening comprehension test Ordinal scaleAdjectives on a word-association test Nominal scalePercentile scores from a spelling test Ordinal scaleSpeed of note-taking in words per minute Ratio scaleI
2、.Q.-equivalent scores on a vocabulary test Interval scalez-scores on the TOEFL Interval scaleThe number of instrumentally motivated students in class Nominal scale2Given the following raw score distribution on a spelling test of 25 items, calculate (a) ordinal ratings, (b) percentage scores, (c) per
3、centile ranks: 6, 8, 9, 11, 12, 12, 14, 15, 19, 19, 21, 25. Solution:Raw scoresOrdinal ratingsPercentage ScoresPercentile Ranks251st10095.8212nd8487.5193rd7675.0194th7675.0155th6062.5146th5654.2127th4841.7128th4841.7119th4429.2910th3620.8811th3212.5612th244.23If you administered a multiple-choice te
4、st of phrasal verb usage to a class of ten students and got the following distribution of scores: 11, 13, 16, 16, 18, 20, 20, 25, 27, 29, what would be the corresponding z-scores, T-scores, and normal distribution area proportions if the standard deviation is 5.95?Solution:Raw scoresz-scoresT-scores
5、Normal distribution area proportions291.59765.9794.49271.26162.6189.63250.92559.2582.24200.08450.8453.35200.08450.8453.3518-0.25247.4840.0516-0.58844.1227.8116-0.58844.1227.8113-1.09339.0713.7311-1.42935.717.654In a normal distribution, what proportion of the scores lie between plus and minus one st
6、andard deviation? Between plus and minus two standard deviations?Solution:In a normal distribution, 68.3% of scores lie between plus and minus one standard deviation;95.5% of scores lie between plus and minus two standard deviation.5Compute item difficulty and the proportion incorrect for each of th
7、e items in the following scoring matrix. Identify items for rejection. Items12345110111211000311001Examinees4101015010006111107110018010109110011001101Solution:Item12345Difficulty0.70.80.40.30.6Proportion incorrect0.30.20.60.70.4Items 2 and 4 can be rejected, because it seems that item 2 is too easy
8、 and item 4 is too difficult.6Look at the following paired scores on listening comprehension (X) and general proficiency (Y) for ten students: XY2518132115221927173116222129243322262129Compute the correlation coefficient for these scores. Please do a one-tailed Pearson test to determine whether it i
9、s significant on the level of significance of .05?Solution:r=0.273.The critical value for Pearson r of the significance of .05, one tailed test when the degree of freedom equals to 8 is 0.5494. Since r=0.2730.5494, it is not significant.7Nine students have taken two different aptitude tests and got
10、the following test result. Compute the Pearson product moment correlation coefficient. And determine whether it is significant on the level of significance of .05? Student No.010203040506070809Test A566061626567717174Test B342662303028343640Solution:r=-0.0176.Critical value is 0.6664. And r=-0.01760
11、.6664, so it is not statistically significant.8Look at the following scoring matrix for twenty students: ItemStudent12345Score1101114211001330101024010012511110461101147101013801011391101141011010311001012120101131311010314110013151111151601001217011103181001131901011320111115Compute the point biser
12、ial correlation coefficient for each of the five items with total score.Solution:Item One: 0.639Item Two: 0.112Item Three: 0.422Item Four: 0.512Item Five: 0.1299What do we mean by correlation in statistics? Solution:Correlation is a statistical relation between two or more variables such that system
13、atic changes in the value of one variable are accompanied by systematic changes in the other. Generally, correlation does not suggest cause-effect relationship.10Please state the difference between the classroom tests and external tests.Solution:The aim of the classroom test is different from that of the external examination. External examinations are generally concerned with evaluation for the purpose of selection, the classroom test is concerned with
