The reliability of the instrument used to obtain responses on the variables can be tested. Although we concentrate largely on how to use spss to get. Calculating, interpreting, and reporting cronbachs alpha reliability. While true or not the data is highly dependent on true or not the research instrument. Testing the validity and reliability of the levels of self. Quantifying testretest reliability using the intraclass. Reliability statistics cronbachs alpha cronbachs alpha based on standardized items n of items. In some cases, thirdparty developed functions are available. Calculating and interpreting cronbachs alpha using spss. Spss provides a measurement of internal consistency reliability of the test items called cronbachs alpha. This type of reliability assumes that there will be no change in the quality or construct being measured.
Reliability analysis dialogue box for cronbachs alpha in spss statistics. Calculating total scale scores and reliability spss. To the discharge of testretest users, it must be acknowledged that correct methods for agreement, such as blandaltmans plot or the concordance correlation coefficient, are still not yet directly available in standard commercial statistical packages, such as sas, stata, and spss. Transfer variables q1 through q5 into the items, and leave the model set as alpha. In analyzing the data, you want to ensure that these questions q1 through q5 all reliably measure the same latent variable i. Splithalf reliability is an internal consistency measure of reliability where two equal halves of a survey are correlated. This can be illustrated using a simple data set of actual data collected from a class of graduate students enrolled in a winter quarter, 2003, research design course. How to test validity questionnaire using spss the validity and reliability the instrument is essential in research data collection.
Click on to return to the main dialog box and then click to run the analysis. How to test validity questionnaire using spss spss tests. For data measured at nominal level, eg agreement concordance by 2 health professionals of classifying patients at risk or not at risk of a fall, use of cohens. Cronbachs alpha is a test reliability technique that requires only a single test administration to provide a unique estimate of the reliability for a. Cronbach alpha is a reliability test conducted within spss in order to measure the internal consistency i. Listwise deletion based on all variables in the procedure. In the correlations table, match the row to the column between the two observations, administrations, or survey scores. Cronbachs alpha can be carried out in spss statistics using the reliability analysis.
The slope is given in the b column to the right of the name of the x variable. Exploratory and confirmatory factor analyses for testing. Questionnaire evaluation with factor analysis and cronbachs alpha an example melanie hof 1. How to use spsscronbachs alpha reliability test youtube. Cronbachs alpha in spss statistics procedure, output and. There were three items that were negatively keyed that needed to be rescored. In this section, we set out this 7step procedure depending on whether you have version 26 or the subscription version of spss statistics or version 25 or earlier. Each chapter deals with a different type of analytical procedure applied to one or more data sets primarily although not exclusively from the social and behavioral areas.
Quantifying testretest reliability using the intraclass correlation coefficient and the sem. Reliability analysis on spss lets test the reliability of the saq using the data in saq. Testretest reliability is applicable in spss research when the test would administer twice at two different points of time. You can also view the video on youtube through this link. 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.
Questionnaire evaluation with factor analysis and cronbach. For more information about reading data in spss, see the spss command syntax reference. Use the simple set of options in figure 2, to run a basic reliability analysis. Just as we would not use a math test to assess verbal skills, we would not want to use a measuring device for research that was not truly measuring what we purport it to. If the test is doubled to include 10 items, the new reliability estimate would be. Reliability and validity testing of a new scale for measuring attitudes toward learnig statistics with techology 3 volume 4 number 1, 2011 a factor, must load to it more than 0. You can also use the dropdown menu in spss, as follows. A reliability analysis was carried out on the perceived task values scale comprising 8 items. Ave can be calculated by using auto design by james gaskin by visiting this website, and click on excel stattools on the left hand menu, it is an excel file with calculator for calculating ave, reliability and validity test.
Ask for two scores, cronbachs alpha and gutmmans lambda guttmans lambda w. First, the keisermeyerolkin kmo test for sampling adequacy and bartletts test for sphericity was done to ensure that the efa was adequate for principal component analysis pca. Remember, in spss one row has to contain all of the data for one participant. The pearson correlation is the testretest reliability coefficient, the sig. Korb university of jos i administered a 10item spelling test to 15. The example here is based on a fictional study that aims to examine students motivations to. The test retest reliability and pilot testing of the. Feldt, 1965, which has been implemented in spss, assumes parallel. There are versions of spss for windows 98, 2000, me, nt, xp, major unix platforms solaris, linux, aix, and macintosh. Whenever a test or other measuring device is used as part of the data collection process, the validity and reliability of that test is important. Exploratory factor analysis efa was ap plied to the six items of the questionnaire. The higher the correlation among the items, the greater.
To test the internal consistency, you can run the cronbachs alpha test using the reliability command in spss, as follows. The following exercise gives you some practice in this process. Calculating, interpreting, and reporting cronbachs alpha. Click the options button, and check variance under. From the top menu, click analyze, then scale, and then reliability analysis. How to use spsscronbachs alpha reliability test thermuohp biostatistics resource channel. Cronbachs alpha is reported using the small greek letter alpha. Moreover, each factor must have more than two variables. This article provided a basic idea about the usage of cronbachs alpha to test statistically reliability of quantitative data. After the research instrument is declared invalid in the validity of the test, then the next step i will give an example of reliability test method alpha method using. How to test reliability method alpha using spss instruments are valid and reliable research is a necessary condition to obtain highquality research results. Another common misconception is that reliability is equivalent to validity. In figure 1 a, weve tted a model relating a households weekly gas consumption to the average outside temperature1. Cronbachs alpha reliability test using spss duration.
Results from the reliability analysis revealed that the scales had good internal consistency. In my view, for underresourced settings, any test with fairly good reliability may be better than no test at all, rather than the current apparent false sense of low prevalence of covid19. Validity pertains to the extent to which scores measure the intended concept. Consider the reliability estimate for the fiveitem test used previously. A researcher has devised a ninequestion questionnaire. For more information about intraclass coefficients as a measure of reliability, see spss library. To obtain descriptive statistics, such as mean, variance, skew, and kurtosis. An attitude, for example, can vary from being very favorable to being very. In this book, we describe the most popular, spss for windows, although most features are shared by the other versions.
It is the degree to which an instrument will give similar results for the same individuals at different times. The analyses reported in this book are based on spss version 11. Katherine miller missouri state university fall 2015 this video covers how to run cronbachs alpha in spss for reliability. Scaled euclidean indices of agreement as obvious choices for use in assessing test and rating reliability, test. 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. Now, you should have reverse scored item 3 see above. Suppose you wish to give a survey that measures job motivation by asking five questions. The rankin paper also discusses an icc 1,2 for a reliability measure using the average of two readings per day. At the end of these seven steps, we show you how to interpret the results from your cronbachs alpha analysis.
In spss, how do i compute cronbachs alpha statistic to. Figure 2 interpreting the output spss output 1 shows the results of this basic reliability analysis for the fear of computing subscale. Reliability analysis using spss cronbachs alpha youtube. For example, if the test is increased from 5 to 10 items, m is 10 5 2.
An instructors guide to understanding test reliability. The pearson correlation is the test retest reliability coefficient, the sig. Put all six items in that scale into the analysis 3. Furthermore, to understand the procedure of calculating alpha using spss refer to performing tests using cronbach alpha. The splithalf method measures the correlation between evennumbered and oddnumbered items. Reliability is a measure to indicate that a reliable instrument to be used as a means of collecting data for the instrument is considered good. It is most commonly used when the questionnaire is developed using multiple likert scale statements and therefore to. Internal reliability if you have a scale with of six items, 16, 1. Cronbachs alpha is the most common measure of internal consistency reliability. Table 3 shows the itemanalysis output from spss for the multiitem scale of student. After the research instrument is declared invalid in the validity of the test, then the next step i will give an example of reliability test method alpha method using spss.
The cronbachs alpha coefficients ranged from a low of 0. Most items appeared to be worthy of retention, resulting in a decrease in the alpha if deleted. In most cases, reliability will be higher when little time has passed between tests. This kind of reliability can be tested using cronbach. Therefore, the correct data will be determining true the results of research quality. Using reliability analysis, you can determine the extent to which the items in your questionnaire are related to each other, you can get an overall index of the repeatability or internal consistency of the scale as a whole, and you can identify problem items that should be excluded from the scale. How to test reliability method alpha using spss spss tests. Data analysis using spss new approach statistical analysis research methodology. In reliability analysis these reverse scored items make. This reliability assumed there would be no dissimilarity in the data being measured. Reliability test spss research and analysis service. 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.
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