**8. Distractor analysis**

Commonly are formed of a stem with or without leading question and five or four alternatives (type A MCQs). Among item's alternatives, only one is the key answer and others are called distractors [4]. Distractors should carry or convey a miss concept about the key answer and appear plausible. The distractors should appear similar to the key answer in terms of the used words, grammatical form,


#### **Table 1.**

*Reference values and interpretation of Cronbach's alpha (KR20).*

style, and length [19]. Distractor efficiency (DE) is the ability of incorrect answers to distract the students [12].

A functional distractor (FD) the distractor that is selected by 5% or more of the examinee [4, 33]. At the same time, those chosen by less than 5% of the examinee are considered non-functional (NFD) [4]. In comparison, other authors reported 1% of the examinee as the demarcation of functional distractors [34, 35]. Commonly items are categorized based on the numbers of NFDs in the item (**Table 2**) [12, 26, 36, 37].

The occurrence of NFD makes the item easier and reduces its discrimination power, while FD distractors are making it more difficult [36, 38]. It was reported that non-functional distractors are negatively correlating with reliability [38]. The presence of non-functional distractors can be related to two main causes. First is the training and construction ability of the item writer or composer. Second, the miss-match between the target content and the possible number of a distractor created. Thus, training and more effort in item writing and construction can decrease NFDs [36]. Other causes were related to NFDs, including the low

#### *Item Analysis: Concept and Application DOI: http://dx.doi.org/10.5772/intechopen.100138*

cognitive level of the item, irrelevant or limited number of plausible distractors, or presence of logic cues [39]. Another possibility of NFDs is mastering the content material of the item, and students can identify the distractor as the wrong one. If no other cause (s) for NFDs, they should be removed or changed with a more plausible option because it has no contribution to the measurement of the test [12]. If a distractor is selected more frequently than the key answer by a higher-scoring examinee, this may indicate poor constructions or a misleading question or miss or double-keyed [12, 40]. In this, concerning the use of three options is more practical than four, does not affect reliability, and does not affect the discrimination index significantly [26, 35–37].

Furthermore, it was reported that there is no psychometric reason that all items in the exam should have the same number of distractors [26, 41]. The required number of options in an item should be considered according to the content material from which plausible distractors can be developed [33, 40, 42].

Reducing the number of options/distractors will result in other important benefits such as reducing the answering time of the test and safe time can be used to cover more content material, reduce the burden on item composers, and have items with more acceptable parameters [43, 44].

Puthiaparampil et al. reported a non-high significant negative and positive correlation between the number of functional distractors and difficulty and discrimination indices, respectively [34]. While a significant positive correlation was reported between the DIF and the number of NFDs [45].

Many authors concluded that no predictable relationship between DE and difficulty index and discrimination index [26, 31, 40, 46, 47]. In addition Licona-Chávez et al. did not find a parallel performance between DE and other parameters of item analysis including Cronbach alpha [46]. In contrast, some authors claimed that low DE decreases the difficulty index [47, 48].
