Scientific calculators

How to summarise Likert scale data using SPSS

Elsewhere in this blog, I have written that a Likert scale might consist of several overlapping items. For instance, if I want to measure subjects’ attitudes towards sweets, I might ask them to record how they feel about the following statements:

Strongly Agree Agree Disagree

Strongly Disagree

1.  I like chocolate.
2.  I like cookies
3.  Ι Iike whipped cream

In order to interpret these data, we need to summarise the data in the scale. The safest way to do this is by estimating the median value of all the items. Using the same example as above, I need to create a new ‘super-variable’, which shows the mean of items (1), (2) and (3) for each respondent.

In the paragraphs that follow, I will show how to do this, using SPSS. I assume that you will already know how to define variables and values, how to toggle between the numerical expression and verbal descriptor of the values (i.e., you can make SPSS show responses as “strongly agree/agree/disagree/strongly disagree” or as “1/2/3/4”, and how to key in data. I will also assume that you have already established that the scale is internally consistent, so I will focus only on the technical aspects of merging the variables.

Starting out

Your starting point will be a dataset similar to Figure 1 below.

Sample Dataset
Figure 1 – Sample Dataset

When you have typed in your data, and tested for the internal consistency of the scale (use Cronbach’s α), it’s time to create a new variable.

Merging the variables

From the top menu bar, select Transform -> Compute variable. You should now see the following dialogue box.

Slide2
Figure 2 – Walkthrough
  1. Assign a name to the new variable (e.g., Sweets)
  2. Scroll down the Function Group, and select Statistical
  3. From the functions that appear select the Median. [ΝΒ it is possible to select the mean, but I don’t recommend it]. At this point, the following formula should appear in the numerical expression box: Median ( , )
  4. Place the cursor in the brackets, select the variables you want to merge, and click on the arrow. Repeat with all the variables, separating them with comas.
  5. Click on OK.

Result

SPSS will automatically generate a new variable, which will appear at the end of your dataset. This will be in numerical form (1, 2, 3, …), but you can change it to a verbal descriptor for consistency (Figure 3). You can use this variable for descriptive statistics (e.g., estimate the central tendency and dispersion), cross-tabulations, correlations and so on…

Figure 3 – The new variable

Now wasn’t that very easy?


Featured Image by Michael Kwan [CC BY-NC-ND] 

43 thoughts on “How to summarise Likert scale data using SPSS”

  1. Hi,
    I am doing likert scale questions. However, I use 2 questions under one category as the situation you shown above, there are 3 questions under one category, which is able to calculate the new variable through median. However, for my situation, if I use median, there will be decimal places for the number. How should I do? Please help me. Thank you so much

  2. Hi, As the situation you shown above, you are using three questions for one variable, therefore you calculate median, however for my situation, I am using two questions for one variable, if i calculate median will be not approprate?because demical places.. or should I calculate by mode? I am really do not know how should I do the analysis?

  3. Hi! Thanks for the post. It’s been really helpful. But a quick question. How do I create verbal descriptions if I gave a decimal value?

    1. I’m glad you found it helpful. The reason why you have decimal values is because you have calculated the mean (or ‘average’). As you have intuitively found out, the mean doesn’t make much sense in Likert scales. That’s because the data that these scales produce are ordinal. There are researchers who claim that this is okay, but many people think that this is statistically wrong, and as you’ve found out, the results are hard to interpret. A less controversial thing to do is to calculate the median of the scale.

  4. I have 5 different questions for identifying the mood or response of 1 independent variable. The rating scale is
    5-Strongly Agree
    4-Agree
    3-Neutral
    2-Disagree
    1-Strongly Disagree
    The result of tested internal consistency is alpha 8.45. Now I want to compute the 5 questions having 5 tables into 1 table for my independent variable All questions are in ordinal measure. Some people suggest me to take the average of these 5 question but i see you used MEDIAN. Here im confused as to what should i take ???

    1. I prefer using the median, for reasons that I have explained elsewhere in this blog. Many people use the mean (average), but I think this is not, strictly speaking, sound statistical practice.

  5. ok thanks and after the MEDIAN result table, their measure changed from ordinal to Nominal in SPSS. The original data type was ordinal. Should i leave it nominal or as by question data type, Ordinal ? what should i select between nominal and ordinal ?

    1. I am not sure why it changed. Your scale is Ordinal, as you said. It doesn’t really matter what the SPSS table reads – this is more of a reminder for you. If you are of an obsessive predisposition, you can change it back, but even if you don’t correct it, it shouldn’t affect results.

  6. Hi,

    I’ve a dataset with likert scale questions, in which participants weren’t required to answer all questions. I showed them 4 advertisements in total. I had 2 versions of each advertisement. The questionnaire tool I used assigned each participant randomly to a condition. So for example, participant 1 saw ad 1, version 2, ad 2, version 2, ad3, version 1 and ad 4, version 2. Participant 2 saw ad 1, version 2, ad 2, version 1, ad 3, version 1 and ad 4, version 2 etc. etc.

    I asked the same set of questions (7 questions in total) after having shown each advertisement. These 7 questions combined measured the dependent variable likeability.

    I wanted to combine the answers of the 7 questions, since it measures one dependent variable.

    I used your technique, and SPSS does combine the questions and makes new variables. Now I get: Likeabilityad1version1, Likeabilityad1version2, Likeabilityad2version1, Likeabilityad2version2, Likeabilityad3version1, Likeabilityad3version2, Likeabilityad4version1 and Likeabilityad4version2.

    However, when I want to create a new variable that gives the general likeability of version 1 (so with all the version 1 ads combined) and the general likeability of version 2 (so with all the version 2 ads combined), I get an error. The reason for this is, that SPSS only calculates a result for each participant that either answered the questions for all versions 1 or all versions 2.

    My question is, how can I create a variable with which I can measure if people liked version 1 or version 2 better?

    I’m sorry if this sounds all way too complicated. Please let me know if I need to provide more details. I would really appreciate your help.

    Many thanks in advance!

  7. Hello, I am writing my Thesis about employee satisfaction and I have 50 questions with 5 options: Agree, strongly agree, neutral, disgaree, strongly disagree. It will be very confusing and long if I analyse each question on its own. How can I give a clear overview on the results keeping in mind that I have 350 questionnaires?

    1. I think that despite the risk of seeming confusing and long, the data should be presented in full, for reasons of transparency.

      That said, I imagine that the 50 questions form ‘groups’ of similar questions, with each group measuring one underlying construct (or ‘latent variable’). You may want to summarise the information in these groups, and here’s some advice on how to do that: https://achilleaskostoulas.com/2014/12/15/how-to-summarise-likert-scale-data-using-spss/

      Best of luck with your project!

  8. Dear Sir, I am lookin at impact of three IVs (Perception of Police Fairness, Perception of Police Effectiveness and Perception of Police Moral Solidarity with Community) onDV Police Legitimacy moderated by Perception of Judicary. Likert scale questionares to measure 3 variables were taken from a one source and the the other two were taken from a different source. As such some scales go (1=Strongly Agree to 5 Strongly Disagree) whereas one goes (1= Strongly Disagree – 6 = Strongly Agree). This implies likert values of one variable suggesting a good situation fall close to 1 whereas in the case of second variable scale is such that ‘goodness’ ought to be valued close to 6 or 5. Data has been collected and entered into SPSS. Would this create a problem in analysis ot should I reverse entire variable question groups. Please help

    1. That shouldn’t be a problem, unless you plan to combine the data in some way. However in the interest of making the data interpretation and display clearer, you might want to reverse the codes in one of the scales.

  9. I am conducting an employee engagement survey with 28 questions on a 5 point likert scale. No demegraphics such as age, Male or Femaile ect. was asked. What tests would you suggest running in SPSS to get the best results and show the data is or is not significant.

    Thanks

  10. i followed the steps and i couldn’t find the MEDIAN within the statistical function group. what can i do? and i tried the mean for a 5 likert scale and i found the descriptives in decimals (2- 2.4-2.6-2.8 till 5). how can i deal with it?
    thank you

    1. The median should be there (have a look at the screenshot). If it isn’t, you may want to take that up with the IT services at your university or IBM customer support. But do look carefully before contacting them.

  11. hello i would like to ask how to do if i have two variables (practices and awareness) with 9 questions each… late it would be used to compute for the significant relationship. thank you very much…

  12. Hi Achilea,

    I have a 10 likert scale 1= not at all, 10= very much. I will the subcategories of my questionnaire in order to get the mean as you suggest. Why do you suggest Median instead of Mean? Would you suggest the same for my case?

    Thanks a lot in advance!

    Giorgos

    1. Hi! I wouldn’t call that a Likert scale as such. The scale you’re using produces interval data, and a mean is an appropriate measure of central tendency in this case.

  13. Thanks for the info… I have been looking for discussions about merging likert scales, and also youtube videos bust they all use means but do not explain why, this is the first time I heard using median, which makes a lot of sense.

    1. It means that the relations between the different items are very weak: they seem to be measuring different things. Do not combine them in a single scale!

  14. hey,
    I have the similar question.
    I have 3 question all in scale –
    1 – strongly support,
    2 – support,
    3 – do not support
    4 – strongly do not support
    5 – no answear.

    So maybe you can help figure out, how can I group those 3 questions answers to get 25% respondents who are supporters un 25% who ar not?

  15. Hello,

    I have three questions for each independent variable. I have three independent variables.
    I need to perform Multiple Regression Analysis to find out the relationship between the dependent variable and the independent variable. How do I do this?

  16. dear sir..
    i need help
    my questionnaire is like this [description of questionnaire reducted] i need to do hypothesis testing in spss…. how do i do it…. i really need help…. please help me…

    1. Hi Bijay,

      Your hypotheses will derive from your research questions. It is hard to see how you can confirm or disprove them, without knowing what the research questions are, or any other information about your research project. Your advisor will be able to help you more than I can.

  17. Good day to you Achilleas.

    I have 29 items/survey questionnaire results measured using a 5 point Likert Scale. I’ve created my dependent variable for analysis, by calculating the median for these 29 items. When I run an ordinal regression or factor analysis, none of the data seems usable. To be clear, my dependent variable is ‘perceived effectiveness’, to be influenced by the categories of financial management, data collection, etc. with the 29 survey questions falling into these categories. Should I enter the category titles somewhere? I’ve just been using the questions results. Is there something else I should do for the dependent variable. Thank you!!! Cass.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s