The Horst Partial Knowledge Index or PKI (Maxinity terminology) is a statistic which can be used to help understand and consequently improve item reliability. It is particularly useful at identifying problem items, as a negative Horst PKI indicates that more candidates answered a question with a specific wrong answer (most popular distractor) than the correct answer.
The PCC measures the strength of the relationship between two variables - in an exam this would be between candidates’ item/question/scenario marks and their exam marks. The Pearson's Correlation attempts to draw a line of best fit through the data points plotted on a graph, and the coefficient evaluates how far away from the line of best fit these data points are.
Are you considering or do you already use point biserial to analyse items in your exams? Our view is that it is useless for all but the simplest of tests - read more to find out why.
The discrimination index (DI) measures how discriminating items in an exam are – i.e. how well an item can differentiate between good candidates and less able ones. For each item it is a measure based on the comparison of performance between stronger and weaker candidates in the exam as a whole.
Item analysis uses different statistical measures in order to determine any problems with the ‘items’ that make up a question in an exam, and hence the question itself. Are your questions working as they should?
When developing a medical or dental examination, it is likely that you will want to include essential and ranking questions - but does your marking scheme discriminate between them?
Standard setting is a way to define levels of achievement or proficiency in an exam and the cut-off marks corresponding to those levels. We summarise the methods and advantages of each, as well as where they are most appropriate.
What is Ebel, and is it right for standard setting your exam? We explain all in our latest installment of our Standard Setting Simplified series.
What is the Cohen method and is it right for standard setting your exam? Find out in the latest installment of our Standard Setting Simplified series.
What is Angoff and when should you use it? Get up to speed on the basics of Angoff and how the method is calculated in the second instalment of our Standard Setting Simplified series.