If the variables are dichotomous 0,1, the coefficient alpha is equivalent to the kuderrichardson 20 kr20 reliability measure. Kudar richardson 20 is run the exact same way as cronbachs alpha in spss and interpreted the same way as well. In psychometrics, the kuder richardson formula 20 kr20, first published in 1937, is a measure of internal consistency reliability for measures with dichotomous choices. Where the questions in a test all have approximately the same difficulty i. Kuder richardson reliability coefficients kr20 and kr21. Although cronbachs alpha is usually used for scores which fall along a continuum, it. The reliability coefficient of the tool has been calculated 0. This analysis applied kr20 to determine reliability within the range of 0.
Can spss calculate the kuder richardson 20 kr20 and kr21 coefficients of reliability for a scale. Note that the matrix or ame should be at the item level and that it needs to be numeric not characters or factors. How to do statistical analysis for test test reliability. Measuring the validity and reliability of research instruments.
It is a measure of how difficult the question was to answer. 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. The scores are compared and expressed as a percentage of agreement or a correlation coefficient expressed as a kappa or k greater than 0. With negative correlations between some variables, the coefficient alpha can have a value less than zero. Using and interpreting cronbachs alpha university of. 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. Determine the reliability of the questionnaire using kuder and richardson formula 20. Instrument reliability educational research basics by. The measure can be viewed as an extension of the kuder richardson formula kr20, which is an equivalent measure of dichotomous items. C it is cronbachs alpha coefficient that provides estimates of homogeneity when instruments are scaled with ordinal responses. The reliability of the instrument was evaluated by assessing internal consistency kuder. The most useful measure is generally the kuder richardson formula 20 kr20.
Scale reliability, cronbachs coefficient alpha, and violations of essential tauequivalence with fixed congeneric components. The instruments reliability was evaluated by assessing the internal consistency kuder richardson coefficient and reproducibility testretest reliability. 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 formula kr20 and the kuder richardson formula 21 kr21. They also confirmed the instruments content validity and reliability using the kuder richardson coefficient, which was 0. This work is licensed under a creative commons attribution. When the correlation between each pair of variables is 1, the coefficient alpha has a maximum value of 1.
Generally, if the reliability of a standardized test is above. The values for reliability coefficients range from 0 to 1. Online statistics helps you in estimating the test reliability using kuderrichardson formula 21 calculator. Performing a reliability analysis on a measurement tool in which the items are dichotomous. 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. The kr20, or kuder richardson formula, measures overall test reliability. If the variances of the items vary widely, you can standardize the items to a standard deviation of 1 before computing the coefficient alpha. Kudar richardson 20 cannot be used for response sets that have three or more levels. The kr20 is a special case of cronbachs alpha in which the items are binary variables usually scored as 0 or 1. It can be shown mathematically that the kuder richardson reliability coefficient is actually the mean of all splithalf coefficients. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 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.
The test was able to distinguish between cts of nursing and philosophy students. Should i use kr20 or kr21 to calculate the reliability coefficient of a test. There are two slightly different versions based on different statistical assumptions. Kuder r1 kr20 coefficient for the data in range r1. The values of p in row 18 are the percentage of students who answered that question correctly e. In psychometrics, cronbachs alpha coefficient of reliability in the special case of a scale with passfail, yesno, or other dichotomous test items. Moreover, the average item discrimination index of achievement test has been found 0. The kuder richardson kr20 coefficient provides estimates of homogeneity used for instruments that have a dichotomous response format. Substituting the required values, yields the equality.
D the kuder richardson coefficient does not apply to this answer. Correlation between forms, guttman splithalf reliability, spearmanbrown reliability equal and unequal length, and coefficient alpha for each half. Assessment of psychometric properties of the brazilian. Kuder richardson 21 calculator chisquare calculator. 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. Cronbachs alpha is a measure used to assess the reliability, or internal consistency, of a set of scale or test items. 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. If the variables are dichotomous 0,1, the coefficient alpha is equivalent to the kuder richardson 20 kr20 reliability measure. Using reliability, validity, and item analysis to evaluate. The kudar richardson 20 kr20 formula generates a raw reliability coefficient for survey items that use these response sets. The kr20 is used to evaluate internal consistency among dichotomous variables. The kudarrichardson 20 kr20 formula generates a raw reliability coefficient for survey items that use these response sets. An example of such a set of commands is provided below, however, kr20 is generally considered to be a better reliability estimate than kr21. 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.
It is often claimed that a high kr20 coefficient e. The results are listed in the upper portion of figure 1. 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 evaluation of the psychometric properties of the brazilian version of the oak test included the analysis of reliability and validity. How to do statistical analysis for test test reliability of a nominal scale in spss. Rumus uji reliabilitas teknik non belah dua non splithalf technique. 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. This is a measure of the likelihood of obtaining similar results if you readminister the exam to another group of similar students. Essentially it lets you know whether the exam as a whole discriminated among students who mastered the subject matter and those who did not. Kuder and richardson formula 20 real statistics using excel.
Matlockhetzel, simui and rasiah 2006 mitra, nagaraja, ponnudurai and judson 2009 and boopathiraj and. Kudarrichardson 20 is run the exact same way as cronbachs alpha in spss and interpreted the same way as well. Ranges from 01 the higher the better greater than 0. The name of this formula stems from the fact that is the twentieth formula discussed in kuder and richardsons seminal paper on test reliability. I use the kr20 instead of the cronbachs alpha because my items are noted on a binary scale. In spss 15 the same sample statistics are computed as in statistica.
I want to use the kr20 to learn about the internal consistency of items. You can select various statistics that describe your scale and items. Kuderrichardson 20 kr20 scale reliability calculation. Cronbachs alpha, intraclass correlation, kuder richardson formula. This work is licensed under a creative commons attributionnoncommercialsharealike license. Differences between kuderrichardson formula 20 and. 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. Cronbachs alpha continuous and dichotomous data in spss.
Computes the reliability coefficient of a set of dichotomous items, whereas cronbachs alpha is used for multipoint scales. Figure 1 kuder and richardson formula 20 for example 1. Kuder richardson 20 kr20 scale reliability calculation can spss calculate the kr20 reliability figure for assessing scales that are composed of dichotomous items. 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. Kr20 kuder richardson formula 20 is an index of the internal consistency reliability of a measurement instrument, such as a test, questionnaire, or inventory. This calculates kuder richarson 20 for a given matrix or ame. 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. Can some one please tell me when i can use the kurder richardson 21 formula, kr20 coefficient alpha or spearman. The aim of this study was to evaluate the psychometric properties of the brazilian version of the oral anticoagulation knowledge oak test. Should i use kr20 or kr21 to calculate the reliability. This video demonstrates how to perform a kuder richardson 20 kr20 test of internal consistency in spss.
Kuderrichardson reliability coefficients kr20 in spss. Although some recommend using the kr20 kuder richardson coefficient if the data are dichotomous, cronbachs coefficient alpha and kr20 yield the same value. Statistics that are reported by default include the number of cases, the number of items, and reliability estimates as follows. Dear all, i am checking how to do a kuderrichardson reliability coefficients kr20 in spss. How to use spss kuderrichardson20 kr20 reliability. Since all tests have some error, reliability coefficients never reach 1. A computer program such as spss is often used to calculate cronbachs alpha.