Interpret questions q1 through q6 based on the data in figure 1 where the 20 students with the highest exam scores high are compared with the 20 students with the lowest exam scores low. Two principal measures used in item analysis are item difficulty and item discrimination. Physical demands, temporal demands, own performance, effort, and frustration. When an alternative is worth other than a single point, or when there is more than one correct alternative per question, the item difficulty is the average score on that item divided by the highest number of points for any one alternative. It is frequently measured by calculating the proportion of individuals passing an item. Item discrimination if the test and a single item measure the same thing, one would expect people who do well on the test to answer that item correctly, and those who do poorly to answer the item incorrectly. One problem with this type of difficulty index is that it may not actually indicate that the item is difficult or easy. A developer is interested in deriving an index of the difficulty of the average item for his math test. Identifying the item deemed to be average in difficulty and then deriving an itemdifficulty index for that item. Item difficulty information from individual timss 2015 items should provide valuable insight into student learning by providing evidence about what the student knows or is able to do. A logit scale is used to express item difficulty on a linear scale that extends from negative infinity to positive infinity. The closer the difficulty of an item approaches to zero, the more difficult that item is. Compute a difficulty index for each item for instructed and uninstructed groups.
Such an item does not discriminate at all between good and poor students, and therefore does not contribute statistically to the effectiveness of. In all cases, however, the purpose of item analysis is. It is a measure of the proportion of examinees who answered the item correctly. Item analysis allows us to observe the item characteristics, and to improve the quality of the test gronlund, 1993. As his consultant on test development, you advise him that this index could be obtained by. The nasa task load index is a multidimensional rating procedure that provides an overall workload score based on a weighted average of ratings on six subscales. The relationship between complexity taxonomy and difficulty.
Free example of item analysis essay essays writers. Item and test analysis to identify quality multiple choice. In order to increase efficient use of both the examiners and the examinee s time, the item difficulty index values can be used to order the administration items so that a discontinue rule can be invoked to reduce the administration of more difficult items to individuals who would be unlikely to pass them. Internal consistency is calculated using the spearmanbrown formula based on a splithalf techniques that compares two. The higher the difficulty index, the easier the item is understood to be wood, 1960. More often, it is a sign that the item has been miskeyed. Evaluate how items discriminate between masters and nonmasters for each objective. Item analysis interpretation real statistics using excel. The more students got the item right, the less difficult the item was. Students fill in blanks with index information after reading a passage. Law school admission test the data set in this example comes from the law school admission test lsat. Employ a printable reading activity that helps build skills in your class using an index.
Item analysis report item difficulty index questionmark. When frank baker wrote his classic the basics of item response theory in 1985, the field of educational assessment was dominated by classical test theory based on test scores. Determine the difficulty index and discrimination level for any essay test item. Analysis of the difficulty and discrimination indices of. As the proportion of examinees who got the item right, the pvalue might more properly be called the item easiness index, rather than the item difficulty.
To determine the difficulty level of test items, a measure called the difficulty index is used. Pvalues are found by using the difficulty index formula, and they are reported in a range between 0. The rasch model, named after georg rasch, is a psychometric model for analyzing categorical data, such as answers to questions on a reading assessment or questionnaire responses, as a function of the tradeoff between a the respondents abilities, attitudes, or personality traits and b the item difficulty. However, item 1 was answered correctly by a person who has high proficiency 83% whereas item 6 was not the person who answered it has 33% proficiency. Here the total number of students is 100, hence, the item difficulty index is 75100 or 75%. The first section describes item difficulty and discrimination indices. Score items 0,1 for each trainee in the instructed and uninstructed groups.
Difficulty index teachers produce a difficulty index for a test item by calculating the proportion of students in class who got an item correct. For example, classical test theory or the rasch model call for different procedures. A simple guide to the item response theory irt and rasch. In general, items should have values of difficulty no less than 20% correct and no greater than 80%. Item difficulty is the percentage of learners who answered an item correctly and ranges from 0. Distracter analysis a multiple choice item has a low difficulty index p example. Item response theory was an upstart whose popular acceptance lagged in part because the. Item analysis should be utilized to improve existing tests instead of developing new items to avoid wastage in time 9. Item analysis basic concepts real statistics using excel. Item analysis examples so, a test item may have an item difficulty of.
Pdf the use of item analysis for the improvement of. Item difficulty index is calculated for the multiplechoice, matching item tests, etc. For example, an english test item that is very difficult for an elementary student will be very easy for a high. For the difficulty index, 27 testtakers answers the item correctly. Within psychometrics, item analysis refers to statistical methods used for selecting items for inclusion in a psychological test. Item discrimination refers to the degree to which items differentiate among examinees in terms of the characteristic being measured e. Pdf the levels of difficulty and discrimination indices in type a.
Then the fourparameter model can be expressed as p ij dpr. A total of 1243 form 2 students from public schools in penang, kedah, perak, and pahang are employed as sample for this study. Item difficulty is an estimate of the skill level needed to pass an item. In the preceding example table 3, item 1 and item 6 have the same difficulty level. What is the definition of difficulty index answers.
The item difficulty index is often called the pvalue because it is a measure of proportion for example, the proportion of students who answer a particular question correctly on a test. For example, they may be used to estimate a students reading ability or the. The formula for the itemdiscrimination index is d ul u pp where. Optimally, an item will encourage a widespread distribution of scores if its difficulty index is approximately 0. Subtract the difficulty index for the low scores group from the difficulty index for the high scores group. Quantitative item analysis is generally based on the factors, obtained statistically.
The process of item analysis varies depending on the psychometric model. The item difficulty index is one of the most useful, and most frequently reported, item analysis statistics. For example, if a class of 25 students takes a test and 15 get the item correct, the. Some basic item analysis for ability and knowledge tests. The chance score for fiveoption questions, for example, is 20 because. Up and lp indicate the numbers of test takers in the upper and lower groups who pass the item, and u is the total numbers of test takers in the upper group. Item analysis is a technique which evaluates the effectiveness of items in tests. Each question has four choices plus blank if the student didnt answer the question.
Interpreting the item analysis report stony brook university. Assessmentquality test constructionteacher toolsitem. The quality of a test depends upon each items of a test shrama, 2000. When interpreting the value of a discrimination it is important to be aware that there is a relationship between an items difficulty index and its discrimination index.
The items are plotted in terms of item difficulty computed using winsteps and the rasch model formula. For example, if a test is being constructed to predict performance in a. Understanding item analyses office of educational assessment. The use of item analysis for the improvement of objective. High values indicate that the item is easy, while low values indicate that the item is difficult. Difficulty index, discrimination index, sensitivity and specificity of. This percentage is referred to as the item difficulty index, or p. Very difficult or very easy items contribute little to the discriminating power of a test. Analyze descriptive statistics descriptives syntax. Analyze choice of distracters for questionable multiplechoice items. Item characteristic curve models 23 to illustrate how the twoparameter model is used to compute the points on an item characteristic curve, consider the following example problem. The relationship between the item difficulty index and discrimination index for each test item was determined. Item analysis is an examination of a test after its administration remmers et al.
Discrimination index is the difference between the proportion of the top scorers who got an item correct. For many analyses, item difficulties will range from. Item difficulty index item difficulty index the proportion of test takers who answer an item correctly for maximizing validity and reliability, the optimal item difficulty level is 0. The number of students who successfully passed the test has to be divided by the overall number of. Once your variables are scored 0 for incorrect and 1 for correct, find the mean of each of the items to obtain the item difficulty. It is possible that the text in item 6 tends to confuse good students.
For example, if 100 participants answered the item, and 72 of them answered the item correctly, then the p value is 0. Higher cognitive examination items promote critical thinking and are recommended to prepare students for clinical training. Item discrimination if the test and a single item measure the same thing, one would expect people who do well on the test to answer that item correctly, and those who do. This measure asks teachers to calculate the proportion. An item analysis is a valuable, yet relatively easy, procedure that teachers can use to answer both of these questions. Check student understanding by using this activity in class or as a homework assignment. Assessing item difficulty and discrimination indices of teacher.
The efficacy of the proposed item difficulty rubrics is validated by designing different difficulty level items for the course basics of digital systems, and validating the difficulty of the. Failure to adhere to standard itemwriting guidelines may render examination questions easier or more difficult than intended. Evaluation is done with the help of difficulty index and discrimination value, i. Item complexity describes the cognitive skill level required to obtain a correct answer. This measure asks teachers to calculate the proportion of students who answered the test item accurately. In order to increase efficient use of both the examiners and the examinees time, the item difficulty index values can be used to order the administration items so that a discontinue rule can be invoked to reduce the administration of more difficult items to individuals who would be unlikely to pass them. For each group, calculate a difficulty index for the item. A 10 question multiple choice test is given to 40 students. This means that 70% of the test takers passed the item, and more students in the top group than the bottom group got the item correct. What is the item difficulty index of an item if 25 students are unable to answer it correctly while 75 answered it correctly.
868 201 439 436 228 606 428 628 1474 1014 1575 653 1262 1465 259 1320 1039 1406 1329 534 1096 1146 471 902 429 741 376 1370 17 359 56 628 607 541 591 1047 1309 1133 108 1104 242 1304 804