Dr Grande you are resourceful. You have helped me so much. I discovered you in 2015 and I am just so grateful. I am almost at the end of my PhD journey and I think you are brilliant.
The detailed explanation of the variables helps me to gain a better understanding of why we chose to use this form of analysis. Sometimes I get confused with regard to which data analysis to select. These introductions help to provide me with appropriate clarification.
I never realized you could just highlight two of the variables you want to look at an it will run them both (or I suppose more than two, even) together. It's great to see how to control for the pretest, the only reason you run this test. This really puts into perspective how one can control for the pretest effect without using the Solomon research design.
This demonstration really allowed me to obtain a better understanding of pretest and posttest analysis. It was beneficial to learn that ANCOVA controls for the pretest values, allowing us to view the posttest values to determine if there is a significant difference between the control and treatment group. I can see how the use of ANCOVA to analyze pretest and posttest data permits researchers to establish whether or not the information being tested is helpful to the groups being assessed.
Thank you for sharing this video Dr. Grande. I like using pretest and post test data to see if what we are testing is actually helpful to the group we are assessing.
It is so much more helpful for me to understand not only ANCOVA, but other statistical measures as well, when Dr. Grande uses pre- and posttest examples. I think seeing the assumptions tested twice on the same population really drives the point home (i.e. if you're confused during the calculation for pretest, pay closer attention during posttest).
I found this video did a good job in explaining what an ANCOVA does. This will be useful in helping me pick out the cappropriate statistics for my research project.
This video was helpful in understanding how to control for the pretest and the outcomes on the post test using ancova. It gave me insight on how to use ancova.
Thank you so much for this video. It helps so much. I was struggling with how to set up my data and you made it really clear. I would love to see how you would write up these results.
I have recently become interested in pretest and post-test analyses. I have also become more familiar with ANCOVA and was unsure of how this worked together. The video helped clarify this and increased my interest in research.
It is really helpful. I haven't learnt ANCOVA in lesson before but I need to propose ANCOVA in my intervention proposal. You clear my doubts. Thank you very much!
I really liked seeing the pretest and posttest examples because it may be something that I want to do for my research proposal. I feel like I was able to follow the video pretty well and I really liked to see how to rule out covariates.
When learning about pretests and posttests in undergrad, I still agree that a study should have both to find any differences before and after a study has been conducted. I think that even though you are trying to test if a treatment is effective, it would be beneficial to compare the posttest and pretest if the treatment has made a significant impact. This video was helpful in explaining the usefulness and how to analyze the data.
I can see this being very a very popular analysis function to use. There was a lot of good information in this video. If I were actually conducting my experiement, it would certinaly come in handy.
This video was so beneficial to watch. This explanation was everything that I needed to ensure I explain the analysis section of my group's research paper accurately. Thank you for posting!
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This video does a great job explaining the usefulness of pretests and posttests, and demonstrates how to then analyze the data. In my opinion, it would be ideal to use pretests and posttests whenever possible, as I feel they are beneficial in determining group or treatment differences within research.
I still think that excel is easier for me to understand personally but the explanation of this process was pretty straight forward and helped me to understand what an Ancova is used for.
I think that SPSS is much harder to understand via video than learning it in person. I think you would find that SPSS is really a language of its own. Once you learn it though, it becomes much more user freiendly than at first glance. Hopefully one day you will get a chance to use it in person!
This video helped me better understand why pretesting and postesting is important. it was helpful to see where the control and treatment groups varied.
Danielle Duboski I was happy to also see where the control and treatment groups varied. This video was really informative and it was nice to grasp a better understanding of pretest and posttest from watching the video.
Pretty interesting video, learning more about SPSS! Being able to use ANCOVA is conditional; certain assumptions have to be tested. I'm learning that you run the univariate tool to test those assumptions and it's nice to walk through how exactly to do that. I'm sure this will come in handy in the future if/when I'm working in the SPSS program.
So it is important to run an ANOVA before the ANCOVA. Pretest and posttest data appears simple, but it's actually not. Once you know that you can control for covariates and other factors, the data can be useful in many other ways. Thank you for the video.
You make a great point with using the Ancova as opposed to using the statistical data. I liked how this video showed the control group and the treatment group and it's able to be viewed through the chart. It was a great visual.
I think that this video helped me to understand ANCOVA a little more and how to use it. I'm still a little confused because I'm not really good with research and all the tests and terms, but this did help me understand more.
I am using pre and post tests in my research paper so this helps. I actually prefer a pre and post test as a way to analyze the differences in the starting point and the outcomes. I am more familiar with Excel but it was nice to see it done in SPSS.
Watching this was interesting and not just because I like statistics. I will be doing a pre test and post test in my research paper and I am glad I was able to see step by step how this is done
Melissa Clendaniel I'm also using a preteset and posttest in my paper so I think think video will come in handy. Especially because it was broken down into step by step processes.
This is important tool to use in an experimental design or any other design with a pre and post test. I like that it compares between control and experimental group and determine if there is statistical significance and test for assumptions.
I thought this video was really interesting and it was nice to see the pre and post tests to see the differences between the control and treatment groups.
I really liked this video because I can relate it to my research project. This would be great to view if I were to actually conduct the experiment and help me do calculations step-by-step.
if there are 3 levels of the independent (experimental, placebo, control) variables, do the steps above remain the same or is there anything that we should be aware off?
Hi there Dr Grande. Is there a way to obtain a table of multiple comparisons when performing an ANCOVA? My independent variable has three levels (different treatments) within it, my dependant variable is treatment score after, and my covariate is treatment score before. I am wanting to look at the significance values of these treatments but am lost as I am only given a test of between subjects effects which only gives a significance value for all three treatments and so the significance of each treatment against one another is unknown. I am quite new to using this program and perhaps am using the wrong type of analysis. Any advice would be amazing! Thank you.
This is very detailed and at first very intimidating but I think over time and with practice I will be alright. I think the key is to make sure you follow the steps correctly and with more experience I will be fine.
This does seem straight forward. Once I explore SPSS a little more and get familiar with all the features, it seems like after the test scores are recorded the program does the configurations.
Is it the same way of doing it if I have more than one variable in Pre and Post testing,for example 9? And do I do it seperately for each variable, one after another? Thanks!
Hi Dr Grande. Is there any conflict about the assumption of covariant must be unrelated to the independent variable to perform an ANCOVA? If not, how can we analyze the effect of A on B, free from C? (A = categorical (2 categories, independent) variable B = numerical (dependent variable) C = numeric (covariant variable) Both B and C appeared significantly different between the two groups according to t-test.)
Sir, it is very useful for a beginner like me. My doubt is in my data consisting the variables more than one post test. Then how do I analyse the data. I usually prefer REPEATED ANOVA.but I have both control and experimental units. Thank you for your responds
Pre and post tests are extremely important. It helps to see if there are any variances in the data collected during the research. Also the data gathered pre and post test can be used as a comparison when noting the findings/conclusion in the research design.
My question is how to interpret the effect of covariate on the posttest? For example, if it is positive correlated, how could you tell such correlation?
The part that I found most interesting is that in the video the co-variate that we contolled for was the effect of the pre-test. I never would have thought to do that. I really thought that was neat. It may be something that I would do with my research proposal as well because mine is a within subjects design.
Like many others I will be doing a pretest and postest in my paper so I found this video very interesting. I liked seeing how to use ANCOVA to do this although I still find ANCOVA to still be a bit confusing.
This would be great to use in my research project. This is a simple process to see if there is a significant difference in groups based on posttest results.
Bethany Elstrom Yes, this would be great to use for my research proposal as well. I can test to see if a group getting CBT and Therapeutic Horseback Riding is more effective than CBT on its own. LOL.
I did exactly as illustrated on the video and got (.203) sig value for the pretest. Is it significant? Also, is .834 not significant in the same context? Where is the cutoff point?
Easy to understand and I think I would be able to do this if I was working is SPSS. I get confused when the test comes up on a different screen with the test results. When using Excel I like that everything is pretty much done in one screen. I think Dr. Grande was able to explain it though in terms that I could understand.
Brittany Vodzak I also like having everything on one screen, it keeps me on track and helps to steer away from possibly making an error or missing steps.
Brittany Vodzak I agree with your statement regarding the one screen. With so many other details and components to keep track of, I like to keep what I am viewing as simple as possible so I don't miss something key or confuse my information.
hello Dr. Grande, thank you for the video can you please do an experimental study SPSS using pre and post test along with other variables that are also pre and post?
I noticed that you did not run the IV without the co-variance as you did in the previous video. Any particular reason or more due to the type of design- pre-post test?
I liked learning how to use a pretest posttest analysis with ANCOVA. My research project will require a pretest posttest, and it is interesting to see how to run one of these tests. I may also have a covariate to rule out, which makes this video helpful for me.
Rachel Foster My research also requires a pre and post test. This video helped explain how I would use ANCOVA in SPSS to see the statistical significance.
Rachel Foster Yes, that is a good idea. I wonder how often covariates are measured and tested for or even how often the ANCOVA is used to control for the pretest. I've never taken notice when reading research articles.
I understand the significance of wanting to control the pretest and comparing the two groups to the posttest only. When would you want to not control the pretest? Would this be a comparison between the pretest and posttest- would that ever be something you would want to look at?
I have a similar research which I finished. there are 30 subjects in group A and Group B. Group A received treatment there are pre and post data in each group. but the problem is the pre and post data are four parameter and there are repeated measures for large number of data. what analysis will you suggest for my research
can i still conduct ancova if my data for treatment group and control group are different ? in my 50 patients, i just am able to collect 13 results for pretest and post test. for treatment group 10 and for control group 3. can i still use this ancova?
Hellou Todd your videos are really good and helpfull. But I have question about post-hoc test. How Can I conduct this post-hoc correction if I want to see exact differences within one of two group? not only main effect. Thank you very much for any response.
Great question Matus. I would like to see a video on this if there isn't one already. Perhaps we should search You Tube videos by Dr. Grande as he is pretty thorough with regard to ensuring he has covered all of the different options.
I understand this model of test more and more with repetition, when we add C to the Anova that means we are controlling a covariate and checking to see if there is a difference between IV groups and the other DV in the data
I like seeing another example of controlling a covariate using ANCOVA and one specifically, controlling pretest data, seems very useful for real-world application.
Michael Smith I agree about pretesting. If you don't have a base live to go from I think even if your results show a difference you are not getting the whole picture.
Pre and Post Test score is interesting to use when one would like to see a difference in a particular population. The ANCOVA will control values to see if there is a significant difference between the control group and experimental group
I wish that this video was in Excel so I could try it. I will be using pre-test and post-testing in my research proposal, so I'd like to know how to do it in the program I have just for fun. I like the example given in this video. It made the video more applicable to something I can understand. I also have covariates I would need to rule out if I actually did my research proposal, so this was interesting to see.
Jessie Howard I wish it had been in Excel too! Many of us seem to be using the pretest-posttest in our research proposal. Therefore, being able to see that in Excel would have been beneficial.
Jessie Howard Seeing how it's done in Excel certainly would be helpful considering it seems that a majority of the videos were made in Excel as well. Consistency is key.
Jessie Howard This would be great if it were an Excel example, especially, as you mentioned, most, if not all of us will be using this type of statistical measure in our research paper! I'm sure if you propose this to Dr. Grande, he will be more than happy to oblige your request.
So, the ANCOVA for pretest and posttest data analysis will control for the pretest values in order to let us see if there is a difference between the two tx groups. This is becoming easier.