Calculating, interpreting, and reporting cronbachs alpha reliability coefficient for likerttype scales joseph a. Conduct and interpret an internal consistency reliability analysis through cronbach s alpha, the corrected itemtotal correlations and the interitem correlation matrix. So the conclusion, from my observation, may be personal or biased, is that the use consistent scales be used when calculating cronbach s alpha. Cronbachs alpha using spss introduction cronbachs alpha is the most common measure of internal consistency reliability. Uji reliabilitas spss adalah pengujian yang mengukur tingkat konsisten atau kestabilan data kuesioner menggunakan software spss. If you dont have a dataset, you can download the example dataset here. It is used under the assumption that you have multiple items measuring the same underlying construct. Conduct and interpret an internal consistency reliability analysis through cronbachs alpha, the corrected itemtotal correlations and the interitem correlation matrix. It is most commonly used when the questionnaire is developed using multiple likert scale statements and therefore to determine if the scale is reliable or not. So the conclusion, from my observation, may be personal or biased, is that the use consistent scales be used when calculating cronbachs alpha. For validity you need to first look at face validity. Using the alpha option, the corr procedure computes cronbachs coefficient alpha in output 2. Cronbach alpha is a reliability test conducted within spss in order to measure the internal consistency i.
Chad marshall is currently a dba student in the mitchell college of business at the university of south alabama. Richardson purdue university abstract the purpose of this study was to develop an effective instrument to measure student readiness in online. Fortunately, chad marshall wrote a wonderful introduction to cronbachs alpha, below. An exploratory factor analysis and reliability analysis of the student online learning readiness solr instrument taeho yu university of virginia jennifer c. Cronbach s alpha is the average value of the reliability coefficients one would obtained for all. The correlations between variables should be consistently high. After data entry the spss screen should look something like figure 1 below. Tauequivalent reliability is a singleadministration reliability i. In reliability, the spss command for running a cronbachs alpha, the only options for missing data are to include or exclude userdefined missing data. After you finish data entry your spss screen should look something like figure 1 below.
A case is the object which you are measuring in someway. Entering data in spss statistics the one person, one row rule. I am currently evaluating the validity and reliability of a scale. Alpha is a very nice command used to calculate cronbach s alpha for scales. Is cronbachs alpha sufficient for assessing the reliability. Sas and spss macros to calculate standardized cronbachs. It is generally used as a measure of internal consistency or reliability of a psychometric instrument. Cronbachs alpha is most commonly used when you want to assess the internal consistency of a questionnaire or survey that is. Cronbachs alpha in this tutorial you will learn how to produce a simple and commonly used measure of reliability.
It can be used as a text in a class or by those working independently. Cara melakukan uji reliabilitas alpha cronbachs dengan spss. Cronbach s alpha reliability coefficient normally ranges between 0 and 1. It is most commonly used when the questionnaire is developed using multiple likert scale statements and therefore to. First of all, the reverse variable list causes stata to reverse score.
Questionnaire evaluation with factor analysis and cronbach. Questionnaire evaluation with factor analysis and cronbachs alpha an example melanie hof 1. Cronbachs alpha gives us a simple way to measure whether or not a score is reliable. In spss, how do i compute cronbachs alpha statistic to. Each chapter has instructions that guide you through a series of problems, as well as graphics showing you what your. If alpha is specified, then cronbachs alpha is calculated for the scale. Then there are a few options which can be used to finetune the command. This video describes how to calculate and interpret cronbach s alpha using spss. It is most commonly used when you have multiple likert questions in a surveyquestionnaire that form a scale and you wish to determine if the scale is re. Spss statistics sets out its data in a spreadsheetlike manner. Cara melakukan uji reliabilitas alpha cronbachs dengan spss setelah sebelumnya kita telah melakukan uji validitas product momen dengan spss, selanjutnya yang harus kita lakukan agar angket yang digunakan dalam penelitian ini benarbenar dapat dipercaya sebagai alat pengumpul data, maka angket tersebut perlu di uji reliabilitas atau tingkat kepercayaannya.
It is most commonly used when you have multiple likert questions in a surveyquestionnaire that form a scale and you wish to determine if the scale is reliable. Analysis cronbachs alpha reliability in spss spss expert. Cronbach s alpha coefficient increases either as the number of items variables increases, or as the average interitem correlations increase i. Cronbach did not refer to this coefficient as alpha, nor did it recommend using it. Cronbachs alpha reliability coefficient normally ranges between 0 and 1. Apr 28, 2018 how to test reliability method alpha using spss instruments are valid and reliable research is a necessary condition to obtain highquality research results. For more information on cronbachs alpha, see spss library. Calculating and interpreting cronbach s alpha using spss. 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 one way of measuring the strength of that consistency.
Calculating, interpreting, and reporting cronbach s alpha reliability coefficient for likerttype scales joseph a. Now that data are collected, we are interested in determining the cronbachs alpha for both scales, task value and anxiety. Now that data are collected, we are interested in determining the cronbach s alpha for both scales, task value and anxiety. The basic syntax is simply alpha variables in the scale and requires at least two items. Below are stepbystep commands for calculating cronbachs alpha in spss. Andy field page 4 2152006 finally, and perhaps most important, the value of alpha at the very bottom is the cronbachs alpha. Alpha is a very nice command used to calculate cronbachs alpha for scales. Introduction the pleasure writers experience in writing considerably in. Calculating cronbachs alpha in spss improving internal. Cronbachs coefficient alpha provides an indication of the average correlation among all of the items that make up the scale.
Spss once spss has opened up there are several options as to how to import your data o you can open it from an existing file o if the dataset is small, then you could type the dataset in by hand o you can run the tutorial as well as a few more option we will open an existing dataset. Pada postingan kali ini saya akan berbagi cara melakukan uji reliabilitas alpha cronbachs dengan program spss. Cronbachs alpha values are quite sensitive to the number of items in the scale. Table 3 shows the itemanalysis output from spss for the multiitem scale of student. Instrumen dapat dikatakan reliabel bila nilai cronbachs alpha lebih besar dari r tabel. That is, does it look like the item measures what it is. 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. Cronbachs alpha is designed to determine internal consistency of attitude scales. Cronbach s alpha in this tutorial you will learn how to produce a simple and commonly used measure of reliability. Cronbachs alpha in spss statistics procedure, output and. Cronbach s alpha is the most common measure of internal consistency reliability.
An optional parameter n may be given, to specify how many variables to be in the first subset. Enter the data into spss as shown above in table 3. Cara uji reliabilitas spss alpha cronbachs data kuesioner. Dalam program spss metode yang sering digunakan untuk uji reliabilitas adalah dengan menggunakan metode alpha cronbachs.
My personal observation has been that when someone calculatures alpha for a mixture of scales like dichotomous, policychotomous, likert etc, then probability of alpha being negative or low is higher. Reliability statistics cronbachs alpha cronbachs alpha based on standardized items n of items. This model splits the scale into two parts and examines the correlation between the parts. Cronbachs alpha coefficient increases either as the number of items variables increases, or as the average interitem correlations increase i. Cronbachs alpha in spss statistics procedure, output. You would have to calculate the alpha of each of the 8 each contstructs using i assume 5 items each, and one for the 5 items that will form your dependent variable.
Uji reliabilitas dalam hal ini mengacu pada nilai alpha yang terdapat dalam tabel output spss. How to test reliability method alpha using spss instruments are valid and reliable research is a necessary condition to obtain highquality research results. In spss, how do i compute cronbachs alpha statistic to test. Items 1 and 2 are responded using a 6point likert scale. In the dataset, we are investigating the relationship of job satisfaction and job performance, but we need to see whether our job satisfaction measure is internally consistent first. Rumus uji reliabilitas teknik non belah dua non splithalf technique. Penjelasan uji reliabilitas instrumen lengkap uji statistik. Cronbachs alpha is the average value of the reliability coefficients one would obtained for all. Berikut cara melakukan uji reliabilitas spss terhadap data kuesioner. The first important table is the reliability statistics table that provides the actual value for cronbachs alpha 8. Cronbachs alpha the most common measure of internal consistency reliability. Cronbachs alpha if item deleted we can see that removal of any question, except question 8, would result in a lower cronbachs alpha. However, the rules of thumb listed above should be used with caution.
Below are stepbystep commands for calculating cronbach s alpha in spss. With these data now consider how one calculates in spss cronbach s alpha for both scales, task value and anxiety. Uji dilakukan pada taraf signifikasi a sebesar 0,05. In other words, it measures how well a set of variables or items measures a single, onedimensional latent aspect of individuals. Lowmotivated writers perform worse, since they spend less. If the model is split, then the variables are divided into 2 subsets. To that end, it is necessary to test the validity and reliability to determine whether the instrument used in the study are valid and reliable. The principle behind entering data in almost all cases in spss statistics is to enter each unique case on a new row. Calculating, interpreting, and reporting cronbachs alpha. Reliability is normally reported under the head of instrumentation in the methodology section.
Sas and spss macros to calculate standardized cronbachs alpha using the upper bound of the phi coefficient for dichotomous items wei sun, chihping chou, a lan w. Calculating and interpreting cronbachs alpha using spss. Cronbach s alpha measurement of internal consistency. Pada postingan kali ini saya akan berbagi cara melakukan uji reliabilitas alpha cronbach s dengan program spss. 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. So the only way to include cases with more than 50% observed data would be to impute them in a separate step before you run the reliability analysis.
This model is a model of internal consistency, based on the average interitem correlation. For more information about intraclass coefficients as a measure of reliability, see spss library. Questionnaire evaluation with factor analysis and cronbachs. Fortunately, chad marshall wrote a wonderful introduction to cronbach s alpha, below. This model computes guttmans lower bounds for true reliability. Cronbachs alpha is a measure used to assess the reliability, or internal consistency, of a set of scale or test items.
How to use spsscronbachs alpha reliability test youtube. Since cronbachs alpha reliability is sensitive to the number of items in a scale. If you need to learn more about cronbachs alpha, click here to read it. A high alpha indicates that the separate items are correlated. Cronbach s alpha measures the internal consistency of scales that are made up of multiple items. Cronbachs alpha is most commonly used when you want to assess the internal consistency of a questionnaire or survey that is made up of multiple likerttype scales and items. This article focuses on the introduction of theory and practice analyzing cronbachs alpha reliability. Cronbachs alpha measures the internal consistency of scales that are made up of multiple items. Once you are familiar with cronbachs alpha, we can then use spss to calculate it. The purpose of this paper is to show why singleitem questions pertaining to a construct are not reliable and should not be used in drawing conclusions.
Cronbachs alpha reliability analysis of measurement scales. Calculating total scale scores and reliability spss. In the assessment of the internal consistency of an instrument, the present study proposed the cronbachs alphas coefficient to be set at 0. Generally, many quantities of interest in medicine, such as anxiety or degree. Cronbach s alpha is certainly among the most used statistics in the social sciences, but many students and researchers dont really know what it tells us or how to interpret it. An exploratory factor analysis and reliability analysis of. Listwise deletion based on all variables in the procedure. Cronbach s alpha is designed to determine internal consistency of attitude scales. Since the data set contains only one species of fish, all the variables are highly correlated. Pengertian uji reliabilitas menurut sugiarto dan situnjuk 2006, uji reliabilitas reliability adalah pengujian yang menunjukkan apakah suatu instrumen yang digunakan untuk memperoleh. Using and interpreting cronbachs alpha university of. Computing cronbachs alpha in spss with missing data the.