The formula for cronbachs alpha builds on the kr20 formula to make it suitable for items with scaled responses e. This index checks the internal consistency of measurements with dichotomous choices i. Kudarrichardson 20 is run the exact same way as cronbachs alpha in spss and interpreted the same way as well. This video demonstrates how to perform a kuder richardson 20 kr 20 test of internal consistency in spss. The kr20 is used for items that have varying difficulty. To investigate the effect of violating the assumption of equal item difficulty on kuderrichardson kr formula 21 reliability coefficient, 670 eighthand ninth grade students were administered 26 short, homogeneous tests of mathematics concepts and skills. You can select various statistics that describe your scale and items. Hi everybody, i need to calculate internal consistency reliability, using kuderrichardson formula 20 i was wondering if someone can explain how to calculate it using spss 20. How to use spss kuder richardson 20 kr 20 reliability analysis thermuohp biostatistics resource channel. What the formla does is to estimate test reliability. As these are measures of internal consistency, they measure the extent to which all the items measure the same characteristic. To verify whether a course in research methodology improved performance, a similar test was given to. Pada bahasan kali ini kita tidak membahas lebih lanjut tentang rumus kr ini, karena akan dijelaskan pada postingan artikel berikutnya.
An example of such a set of commands is provided below, however, kr20 is generally considered to be a better reliability estimate than kr21. For kr21 all you need is the mean score on the test, the standard deviation, and the number of items k. Computes the reliability coefficient of a set of dichotomous items, whereas cronbachs alpha is used for multipoint scales. I use the kr20 instead of the cronbachs alpha because my items are noted on a binary scale. Item analysis technique to improve test items and instruction 2. A correct question scores 1 and an incorrect question scores 0. When jamovi is calculating cronbachs alpha for internal consistency reliability does it switch to using the kr20 formula kuderrichardson 20 when it detects that the measures are dichotomous. Based on parallel tests administered at the same sitting the kr 20 estimates are compared with alternateform correlations and with oddeven correlations adjusted by the spearmanbrown prophecy formula. Kuderrichardson formula 20 21 correlation is determined from a single administration of a test through a study of score variances 16. Note that the matrix or ame should be at the item level and that it needs to be numeric not characters or factors. I want to use the kr20 to learn about the internal consistency of items. Kuderrichardson reliability coefficients kr20 and kr21.
How to compute reliability using kr21 formula kuder. The approximate sampling distribution of kuderrichardson. Kudarrichardson 20 cannot be used for response sets that have three or more levels. The kuderricharson formula 20, often abbreviated as kr20, and the kuderrichardson formula 21, abbreviated kr21, are measures of internal consistency for measures that feature dichotomous items. Rumus kr 20 dan tutorial cara hitung dengan excel uji. Reliability, kuderrichardson formulapage 1418 sage. Although it can be applied to any test item responses that are dichotomously scored, it is most often used in classical psychometric analysis of psychoeducational tests and, as such.
The reliability estimates are incorrect if you have missing data. This video demonstrates how to perform a kuderrichardson 20 kr20 test of internal consistency in spss. You can use spss reliability command to calculate kr20 just. In addition, kr20 computes the item difficulty proportion of right answers, the average value of item difficulty, the item variance, the itemtest pointbiserial correlation coefficients, and the average value of itemtest correlation coefficients. Alpha should be calculated whenever possible, but kr21 can provide reasonable reliability estimates for tests with dichotomous items. Results obtained by the kudarrichardson formula 20 adapted for use with rkw scoring are compared with three other reliability formulas. The kuderrichardson formula 20 kr 20, for example, calculates a reliability coefficient based on the number of test items k, the proportion of the responses to an item that are correct p, the proportion of responses that are incorrect q, and the variance 2. Finally, the data were entered into the spss statistical software, version 14 and were analyzed using paired ttest and independent sample ttest. Excel spreadsheet to calculate instrument reliability.
Kuderrichardson formula 20, or kr20, is a measure reliability for a test with binary variables i. It was first named as alpha by cronbach 1951, although an earlier version is the kuderrichardson formula 20 often shortened to kr20, which is the equivalent for dichotomous items, and guttman 1945 developed the same quantity under the name lambda2. Top 4 characteristics of a good test your article library. I have created an excel spreadsheet to automatically calculate splithalf reliability with spearmanbrown adjustment, kr20, kr21, and cronbachs alpha. Using and interpreting cronbachs alpha university of. How to use spss kuderrichardson20 kr20 reliability. The most useful measure is generally the kuderrichardson formula 20 kr20. The use of the theoretical distribution for testing hypotheses. Login or register free and only takes a few minutes to participate in this question you will also have access to many other tools and opportunities designed for those who have languagerelated jobs or are passionate about them. Estimates internal consistency reliability given the mean m, standard deviation sd and k the number of items from a specific measure of interest.
It is important to evaluate the process of learning. Kuder and richardson formula 20 real statistics using excel. The kuderrichardson formula 20 is rewritten to be identical with the simplest formula, 21, except for the addition of a term involving the standard deviation. It assess the intern consistency reliability of a test of subtest made up of binary items, two psychometric methods, kuder richardson formula 20. How to use spss kuderrichardson20 kr20 reliability analysis thermuohp biostatistics resource channel. The kudarrichardson 20 kr20 formula generates a raw reliability coefficient for survey items that use these response sets. Expanding the possibilities for continual improvement the kr20, or kuderrichardson formula, measures overall test reliability essentially it lets you know whether the exam as a whole discriminated. It is equivalent to performing the split half methodology on all combinations of questions and is applicable when each question is either right or wrong. Reliability refers to how consistent the results from the test are, or how well the test is actually measuring what you want it to measure. Kuderrichardson reliability coefficients kr20 in spss. Please, can anyone tell me how to write the kuder richardson stata command or to reach it through menus, other than using alpha.
The theoretical distribution is compared to empirical estimates of the sampling distribution to assess how crucial certain assumptions are. Both kr formula 20 and kr formula 21 were used to estimate reliability on each test. Rentang nilainya berada diantara 0 sampai dengan 1. Kuderrichardson method is cumbersome to calculate unless information is already available concerning the proportion of passing. Differences between kuderrichardson formula 20 and. To confirm the reliability of exam, we used kuderrichardson formula 20 kr 20 and the reliability was found to be 0. The kr20 is used to evaluate internal consistency among dichotomous variables. My understanding is that spss does this because cronbachs alpha isnt appropriate for dichotomous variables and just wondering if jamovi did. Untuk perhitungan koefisien reliabilitas dapat dilakukan dengan menggunakan rumus kuderrichardson kr20 dan kuderrichardson kr21. Spss software version 20 and its statistical interpretation. Penjelasan uji reliabilitas instrumen lengkap uji statistik. Item analysis with spss software linkedin slideshare. Using the notation of coefficient alpha and under the assumptions of at least essential tauequivalence, it can be shown that. Secondly, i appologize for linking a file but i could not get the fonts for the formula right.
If all of the scale items you want to analyze are binary and you compute cronbachs alpha, youre actually running an analysis called the kuderrichardson 20. Both kuderrichardson and split half method do not measure the consistency of pupil response from day to day. Ranges from 01 the higher the better greater than 0. The kuder and richardson formula 20 test checks the internal consistency of measurements with dichotomous choices. For example, some items might be very easy, others more. Statistics that are reported by default include the number of cases, the number of items, and reliability estimates as follows. An approximation to the sampling distribution of kuderrichardson reliability formula 20 is derived, using its algebraic equivalent obtained through an itemsbysubjects analysis of variance. This calculates kuderricharson 20 for a given matrix or ame. How do i compute the internal consistency of a scale which. Krl20 and kr21 only work when data are entered as 0 and 1. Splithalf reliability one of the internal consistency measures of reliability in which the instrument is administered once and then split into two halves. The kr21 could be calculated in spss by using the aggregate procedure to save kr21 formula components to an active file, where they could be input into a compute command to calculate kr21. Kuderrichardson method and splithalf method are not appropriate for speed tests. Kr20 read about our exciting partnership with blackboard, inc.