The instrument once designed must be reliable. The reliability test is essential as this will show how much you can rely on your designed instruments. If the instrument is not reliable you cannot move further with it. So it is crucial to first check the reliability of the instrument by entering the small number of data initially. It must be kept in mind that with different sample size the reliability will vary. More will be the number of data more will be the reliability.
So in order to check the reliability of the instrument you must enter the data in the SPSS tool (if you want to know how to enter data please see the “How to enter the data in SPSS” page).
This article aims to guide the students to make their instrument reliable and validate it. The SPSS software allows you to find out the reliability in the following way:
1. First of all select analyze from the tool bar and then go to the scale and select the reliability analysis.
2. The new window will be open. Enter the variables by choosing from the left coroner and placing it in the right side.
3. Once you have selected the variables that are nominal and ordinal the next step is to just click OK. The model is bi-default set as Alpha.
4. The output will be shown in the output window. From where you can see the following tables:
1. First of all select analyze from the tool bar and then go to the scale and select the reliability analysis.
2. The new window will be open. Enter the variables by choosing from the left coroner and placing it in the right side.
3. Once you have selected the variables that are nominal and ordinal the next step is to just click OK. The model is bi-default set as Alpha.
4. The output will be shown in the output window. From where you can see the following tables:
a. Table one will show the statistics that how many variables “N” have been selected for the analysis.
b. Table two will show the value of Cronbach’s Alpha. This value will show that how much your instrument is reliable.
c. The value of Cronbach’s alpha can be from -1 to 1. That is basically showing the percentage of the reliability. 1 means that instrument is 100% reliable. Some researchers believe that the instrument will be considered reliable only if the value is above 80% and others believe that 60% value of Cronbach’s alpha is also showing that the instrument is internally validate and reliable.
I hope that this article will be helpful in explaining the concept of reliability and validity and it will help you to test your own instrument’s reliability.
