You can select various statistics that describe your scale and items. Substituting the required values, yields the equality. There are two slightly different versions based on different statistical assumptions. Kuderrichardson reliability coefficients kr20 and kr21. Computes the reliability coefficient of a set of dichotomous items, whereas cronbachs alpha is used for multipoint scales. The kr20 is a special case of cronbachs alpha in which the items are binary variables usually scored as 0 or 1.
This is a measure of the likelihood of obtaining similar results if you readminister the exam to another group of similar students. The scores are compared and expressed as a percentage of agreement or a correlation coefficient expressed as a kappa or k greater than 0. Assessment of psychometric properties of the brazilian. Kudarrichardson 20 cannot be used for response sets that have three or more levels.
If the variables are dichotomous 0,1, the coefficient alpha is equivalent to the kuder richardson 20 kr20 reliability measure. Penjelasan uji reliabilitas instrumen lengkap uji statistik. When the correlation between each pair of variables is 1, the coefficient alpha has a maximum value of 1. I use the kr20 instead of the cronbachs alpha because my items are noted on a binary scale. This calculates kuder richarson 20 for a given matrix or ame. The measure can be viewed as an extension of the kuder richardson formula kr20, which is an equivalent measure of dichotomous items. Essentially it lets you know whether the exam as a whole discriminated among students who mastered the subject matter and those who did not. The most useful measure is generally the kuder richardson formula 20 kr20. Where the questions in a test all have approximately the same difficulty i. Kuderrichardson reliability coefficients kr20 in spss.
Kudarrichardson 20 is run the exact same way as cronbachs alpha in spss and interpreted the same way as well. How to do statistical analysis for test test reliability. The aim of this study was to evaluate the psychometric properties of the brazilian version of the oral anticoagulation knowledge oak test. How to use spss kuderrichardson20 kr20 reliability. Kuder and richardson formula 20 real statistics using excel.
The kuder richardson kr20 coefficient provides estimates of homogeneity used for instruments that have a dichotomous response format. Online statistics helps you in estimating the test reliability using kuderrichardson formula 21 calculator. Ranges from 01 the higher the better greater than 0. How to do statistical analysis for test test reliability of a nominal scale in spss. The kudar richardson 20 kr20 formula generates a raw reliability coefficient for survey items that use these response sets. In psychometrics, the kuder richardson formula 20 kr20, first published in 1937, is a measure of internal consistency reliability for measures with dichotomous choices. There has been used halving test splithalf and kuder richardson kr 20 formulas. Cronbach has given a formula to find out the reliability by using standard deviations of the scores not only on odd and even items but also the total. The evaluation of the psychometric properties of the brazilian version of the oak test included the analysis of reliability and validity.
Kudar richardson 20 cannot be used for response sets that have three or more levels. 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 consistency responses examined by the rasch model interpretation on person and item reliability are explained with kuder richardson kr20 and coefficient alpha cronbach, 1984 values. Can some one please tell me when i can use the kurder richardson 21 formula, kr20 coefficient alpha or spearman. Matlockhetzel, simui and rasiah 2006 mitra, nagaraja, ponnudurai and judson 2009 and boopathiraj and. Cronbach university of illinois a general formula a of which a special case is the kuder richardson coefficient of equivalence is shown to be the mean of all splithalf coefficients resulting from different splittings of. Kuder richardson coefficient kr 20 the kuder richardson coefficient of reliability kr 20 is used to test the reliability of binary measurements such as exam questions, to see if the items within the instruments obtained the same binary noyes, rightwrong results over a population of testing subjects. The values of p in row 18 are the percentage of students who answered that question correctly e.
Correlation between forms, guttman splithalf reliability, spearmanbrown reliability equal and unequal length, and coefficient alpha for each half. Determine the reliability of the questionnaire using kuder and richardson formula 20. Kuder richardson 20 kr20 scale reliability calculation can spss calculate the kr20 reliability figure for assessing scales that are composed of dichotomous items. In psychometrics, cronbachs alpha coefficient of reliability in the special case of a scale with passfail, yesno, or other dichotomous test items.
Instrument reliability educational research basics by. The reliability coefficient of the tool has been calculated 0. The kr21 formula for reliability is a conservative estimate of internal reliability due to the fact that kr21 results will yield lower data numbers than that of kr20 formula calculations values for kr21 calculation coefficients range from 0. The kr20, or kuder richardson formula, measures overall test reliability. It is often claimed that a high kr20 coefficient e. Using reliability, validity, and item analysis to evaluate.
Should i use kr20 or kr21 to calculate the reliability coefficient of a test. If the variances of the items vary widely, you can standardize the items to a standard deviation of 1 before computing the coefficient alpha. Statistics that are reported by default include the number of cases, the number of items, and reliability estimates as follows. They also confirmed the instruments content validity and reliability using the kuder richardson coefficient, which was 0. It can be shown mathematically that the kuder richardson reliability coefficient is actually the mean of all splithalf coefficients. Moreover, the average item discrimination index of achievement test has been found 0. Since all tests have some error, reliability coefficients never reach 1. Cronbachs alpha is a measure used to assess the reliability, or internal consistency, of a set of scale or test items. Learn vocabulary, terms, and more with flashcards, games, and other study tools. D the kuder richardson coefficient does not apply to this answer. 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.
This analysis applied kr20 to determine reliability within the range of 0. To investigate the effect of violating the assumption of equal item difficulty on kuder richardson kr formula 21 reliability coefficient, 670 eighthand ninth grade students were administered 26 short, homogeneous tests of mathematics concepts and skills. Kuder richardson formula kr20 and the kuder richardson formula 21 kr21. Although some recommend using the kr20 kuder richardson coefficient if the data are dichotomous, cronbachs coefficient alpha and kr20 yield the same value. C it is cronbachs alpha coefficient that provides estimates of homogeneity when instruments are scaled with ordinal responses. Should i use kr20 or kr21 to calculate the reliability. I want to use the kr20 to learn about the internal consistency of items.
The instruments reliability was evaluated by assessing the internal consistency kuder richardson coefficient and reproducibility testretest reliability. Kuderrichardson 20 kr20 scale reliability calculation. The reliability of the instrument was evaluated by assessing internal consistency kuder. Kuder richardson reliability coefficients kr20 and kr21. Generally, if the reliability of a standardized test is above. With negative correlations between some variables, the coefficient alpha can have a value less than zero.
Two formulas kr 20and kr 21 that were developed to estimate reliability. Figure 1 kuder and richardson formula 20 for example 1. Although cronbachs alpha is usually used for scores which fall along a continuum, it. If the variables are dichotomous 0,1, the coefficient alpha is equivalent to the kuderrichardson 20 kr20 reliability measure. This study, conducted in an anticoagulation clinic, included 201 brazilian participants aged over 18 years, who had been using warfarin for more than two months. Kuder richardson 21 calculator chisquare calculator. Rumus uji reliabilitas teknik non belah dua non splithalf technique. Salah satu kelemahan perhitungan koefisien reliabilitas dengan menggunakan teknik belah dua adalah 1 banyaknya butir soal harus genap, dan 2 dapat dilakukan dengan cara yang berbeda sehingga menghasilkan nilai yang berbeda pula seperti terlihat pada contoh c. Measuring the validity and reliability of research instruments.
Dear all, i am checking how to do a kuderrichardson reliability coefficients kr20 in spss. The results are listed in the upper portion of figure 1. Cronbachs alpha continuous and dichotomous data in spss. Can spss calculate the kuder richardson 20 kr20 and kr21 coefficients of reliability for a scale. 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. An example of such a set of commands is provided below, however, kr20 is generally considered to be a better reliability estimate than kr21. The kudarrichardson 20 kr20 formula generates a raw reliability coefficient for survey items that use these response sets. Cronbachs alpha, intraclass correlation, kuder richardson formula. Performing a reliability analysis on a measurement tool in which the items are dichotomous. Kudar richardson 20 is run the exact same way as cronbachs alpha in spss and interpreted the same way as well. Kuder r1 kr20 coefficient for the data in range r1. In other words, the reliability of any given measurement refers to the extent to which it is a consistent measure of a concept, and cronbachs alpha is.
This video demonstrates how to perform a kuder richardson 20 kr20 test of internal consistency in spss. The values for reliability coefficients range from 0 to 1. In statistics classical test theory, cronbachs alpha is a name used for tauequivalent reliability as an lowerbound estimate of the reliability of a psychometric test. Scale reliability, cronbachs coefficient alpha, and violations of essential tauequivalence with fixed congeneric components.
The name of this formula stems from the fact that is the twentieth formula discussed in kuder and richardson s seminal paper on test reliability. Note that the matrix or ame should be at the item level and that it needs to be numeric not characters or factors. It is a measure of how difficult the question was to answer. The test was able to distinguish between cts of nursing and philosophy students. In spss 15 the same sample statistics are computed as in statistica. The kr20 is used to evaluate internal consistency among dichotomous variables. This work is licensed under a creative commons attributionnoncommercialsharealike license. The name of this formula stems from the fact that is the twentieth formula discussed in kuder and richardsons seminal paper on test reliability. Kr20 kuder richardson formula 20 is an index of the internal consistency reliability of a measurement instrument, such as a test, questionnaire, or inventory. Using and interpreting cronbachs alpha university of. A computer program such as spss is often used to calculate cronbachs alpha. This work is licensed under a creative commons attribution. Estimates internal consistency reliability given the mean m, standard deviation sd and k the number of items from a specific measure of interest. Differences between kuderrichardson formula 20 and.