Cara uji reliabilitas splithalf spearman brown dengan. The spearmanbrown coefficient is a measure of interitem reliability. To test for a rank order relationship between two quantitative variables when concerned that one or both variables is ordinal rather than interval andor not normally distributed or when the sample size is small. There are situations where you might want to understand how changes in test length may affect reliability. The following steps were taken in cleaning the data file for the purpose of this study. Average interitem correlation average itemtotal correlation cronbachs alpha splithalf reliability adjusted using the spearmanbrown prophecy formula composite reliability if youre unfamiliar with any of these, here are some resources to get. Spearman brown prophecy formula when test length manipulated there are situations where you might want to understand how changes in test length may affect reliability. The spearmanbrown prediction formula, also known as the spearmanbrown prophecy.
The work of charles spearman combined what two measurement concepts a mean and from co 545 at university of west alabama. Download pdf show page numbers charles spearman and william brown separately derived a formula to predict the reliability of a test page 1403 when its length was altered by the addition or subtraction of parallel items. Spearmanbrown prophecy formula sage research methods. The most common method of dividing a community property interest in sdcers is by using a formula knows as the time rule formula or brown formula. Such an improvement can be estimated using the spearmanbrown prophecy formula. The spearmanbrown formula can be used to predict the effect of lengthening a test on the reliability of the test. Five ways to calculate internal consistency rbloggers. Download download spearman brown formula pdf printer read online read online spearman brown formula pdf printer for a generalized version of classical test theory, lord and novick. Spearmanbrown prophecy formula to defend her tests moderate reliability this way. The primary requirement of a test is validitytraditionally defined as the degree to which a test actually measures whatever it purports to measure. Pdf a direct proof is given for the generalized spearmanbrown formula for any real multiple of test length.
The reliability of a test cronbachs alpha or kuderrichardsons coefficient in case of dichotomous items is dependent of the number of items. The spearmanbrown prediction formula, also known as the spearmanbrown prophecy formula, is a formula relating psychometric reliability to test length and used by psychometricians to predict the reliability of a test after changing the test length. We apologize for any inconvenience this may have caused and are working to. Figure 61 shows a portion of the first section of analysis, which provides score information for each examinee. Download pdf show page numbers charles spearman and william brown separately derived a formula to predict the reliability of a test page 1403 when its length was.
A second procedure for estimating the internal consistency type of reliability is. Thus, this research will build upon cronbachs work and show, via various graphs and a detailed table, the differences between the spearmanbrown formula and the flanaganrulon formula. Comparison of values of pearsons and spearmans correlation coefficients on the same sets of data ja n ha u k e, to m a s z kossowski adam mickiewicz university, institute of socioeconomic geography and spatial management, poznan, poland manuscript received april 19, 2011 revised version may 18, 2011. Cronbachs alpha is an estimate of the reliability of a test score if the items are essentially tauequivalent. Krl20 and kr21 only work when data are entered as 0 and 1. Download pdf show page numbers developed independently by charles spearman 1910 and william brown 1910, this formula page 1054 estimates the reliability of multiitem measures or indexes, and provides an important foundation for the statistical theory of measurement. Excel spreadsheet to calculate instrument reliability. If this assumption is violated the formula does not hold and the. Psychological testing psychological testing primary characteristics of methods or instruments. Because a splithalves test may not have enough questions it will allow you to increase the estimate of reliability.
General form estimates reliability r xx of a test that is n times longer. To add an appropriate sign, just look at the line in your correlation graph an upward slope indicates a positive correlation plus sign and a downward slope indicates a negative correlation minus sign. The work of charles spearman combined what two measurement. The spearmanbrown formula, applied to phi correlations calculated for each pair of item scores, estimated fullscale reliabilities of 0.
This content is now available from statistical associates publishers. A test is reliable to the extent that it measures consistently, but reliability is of no consequence if a test lacks validity. This work is licensed under a creative commons attribution. The reliability estimates are incorrect if you have missing data. Buka file data spss bernama untitled validitas corrected item total correlation. Spearman s rankorder correlation analysis of the relationship between two quantitative variables application. This video demonstrates how to compute splithalf reliability and the spearmanbrown coefficient using spss. To be sure, the spearmanbrown formula is usually derived under the assumption that we have parallel items, which implies among other things that the items have equal difficulty. Please be advised that we experienced an unexpected issue that occurred on saturday and sunday january 20th and 21st that caused the site to be down for an extended period of time and affected the ability of users to access content on wiley online library.
A comparison of the spearmanbrown and flanaganrulon. Spearman s coefficient of rank correlation, denoted by rs, can be calculated by applying the formula for the pmcc to the ranks, although it is more usual to use the equivalent, but more algorithmic, formula 2 s 2 6 1 1 di r nn. When this is the case, you 1st obtain cronbachs alpha for the original length test then apply the spearman brown prophecy forumula. Overview researchers must demonstrate instruments are reliable since without reliability, research results using the instrument are not replicable, and replicability is fundamental to the scientific method. This formula is called the spearmanbrown sb formula because the idea was introduced by both c. Reliability statistics cronbachs alpha part 1 value. View of first section of results from view full results command. Rumus spearman brown, rumus flanagent, rumus rulon, rumus. Rsquared is always a positive number, hence the deduced spearman rank correlation coefficient will also be always positive.
Click here below is the overview and table of contents in unformatted form. When would one use cronbachs alpha over the spearmanbrown. A simple proof of the spearmanbrown formula for continuous test. To examine the biases for both tauequivalent and congeneric measures, we. Most if not downright impossible, when ipad my file a i do how read pdf on used in the previous chapter. I have created an excel spreadsheet to automatically calculate splithalf reliability with spearmanbrown adjustment, kr20, kr21, and cronbachs alpha. Primary characteristics of methods or instruments britannica. The spearman brown prediction formula, also known as the spearman brown prophecy formula, is a formula relating psychometric reliability to test length and used by psychometricians to predict the reliability of a test after changing the test length. When ties are present, this coefficient acquires a more complicated formula, but will still be onehalf the reciprocal of the variance of the ranks assigned to the data.
It is possible to greatly increase the reliability by significantly lengthening the test, however sometimes adding 100 items is not plausible. Conclusion this simple webbased program provides a convenient means of estimating the reliability of rating data without the need to conduct special studies in order to provide complete rating data. Rumus spearman brown, rumus flanagent, rumus rulon, rumus kr21, rumus hoyt, rumus alpha cronbach. For example, i often work with a decisionmaking variable called recklessness. Chapter 8 correlation and regression pearson and spearman. And from this, after some twist and turns and the notalwaysfriendly intervention of william brown, we end up with what is generally known today as the spearmanbrown reliability or prophesy formula.
Jika belum punya, maka anda dapat mendownloadnya sekarang melalui link download data. The spearmanbrown prophecy formula provides a rough estimate of how much the reliability of test. It indicates magnitude and direction of the association between two variables that are on interval or ratio scale. Can we use the spearman can we use the spearmanbrown. Validity and reliability of scores obtained on multiple. Several authors have derived results that provide alternative interpretations of alpha. Then, these coefficients are entered into the spearmanbrown formula to yield the splithalf reliability coefficient. These interpretations are also valid if essential tauequivalency does not hold.
The spearmanbrown formula was then used to correct. Reliabilitas reliabilitas menunjuk pada tingkat keterandalan instrumen, apabila datanya memang benar sesuai kenyataannya maka berapa kalipun diambil tetap akan memperoleh hasil yang sama. Pdf a simple proof of the spearmanbrown formula for continuous. Spearman brown prophecy formula when test length manipulated. Although i feel a little sheepish contradicting both a respected text as well as another cv user, it seems to me that the spearmanbrown formula is not affected by having items of differing difficulty. The spearmanbrown formula predicts that by doubling the test. Should i use kr20 or kr21 to calculate the reliability. Julia lathrop39 apparently encouraged by the actor, for an even more so than contemporary comics the processes involved in, the adaptation of the spearmanbrown correction formula. The spearman brown formula assumes that the splithalves are parallel measures.
The assumption of the spearmanbrown formula is that splithalves are parallel, which means that the. Cara uji reliabilitas splithalf spearman brown dengan spss 1. Splithalf reliability and the spearmanbrown coefficient. Some relationships between cronbachs alpha and the. The spearmanbrown prophecy formula provides a rough estimate of how much the reliability of test scores would increase or decrease if the number of observations or items in a measurement instrument were increased or decreased.
Example 1pearson regression an instructor wants to determine if there is a relationship between how long a student spends taking a final exam 2 hours are allotted and his or her grade on the exam students are free to depart upon completion. If you have a likert scale or other types of items, use the spearmanbrown formula. To continue viewing the full analysis, use the down arrow in the lower right portion of. Developed independently by charles spearman 1910 and william brown 1910, this formula page 1054estimates the reliability of. A direct proof is given for the generalized spearmanbrown formula for any real multiple of test length. A pearsons r or spearmans rho correlation is run between the two halves of the instrument.
Alternative estimates of the reliability of college grade. The spearmanbrown formula also called the spearmanbrown prophecy formula is a measure of test reliability. For a generalized version of classical test theory, lord and novick 1968, chapter 5 proved the wellknown spearmanbrown formula for the reliability of a lengthened test. Additionally the program will estimate the reliability of an average of a number of ratings for each subject via the spearmanbrown prophecy formula. Lets get psychometric and learn a range of ways to compute the internal consistency of a test or questionnaire in r. For a twoitem scale the spearman brown coefficient is always larger than coefficient alpha see table 1, except for the case when 1 2 var var.
Letter names, word reading fluency, and passage reading fluency revised december 2011 chalie patarapichayatham. The method was published independently by spearman 1910 and brown 1910. The correction entailed a weighting formula for points awarded for correct answers, incorrect answers, and unanswered questions such that the expected value of increase in test score due to guessing was zero. It is similar to pearsons product moment correlation coe cient, or pearsons r. Using the spearmanbrown prophecy formula to improve medical. The general caseif the component tests are not parallel, then the spearmanbrown formula will wither over or underestimate thereliability of a longer test. Can some one please tell me when i can use the kurderrichardson 21 formula, kr20 coefficient alpha or spearmanbrown formula to calculate the reliability coefficient of a test. The spearmanbrown prediction formula also known as the spearmanbrown prophecy formula is a formula relating psychometric reliability to test length. For example, alpha is the mean of all splithalf reliabilities if the test is split into two halves that are. Using this formula, the former spouses share of benefits is determined taking 50% of a fraction where the numerator is the service credit earned by the member during the marriage and. This formula shows explicitly the relationship of the length of the tests to their intercorrelation pp.
1551 533 338 256 1340 59 255 849 120 676 394 1450 937 1274 1281 217 1172 924 1077 156 1326 586 10 725 358 1008 1243 332 663 1059 1029 529 894 525 40 757