If you open SPSS and run the example that I sent you, will see the within and between-subjects effects in the various tables produced by the program. The within-ss effect answers the question, "Is there a change over time on average," the between-ss effect, "Is there a difference between the means of the groups," while the time*group interaction test answers the question, "Do the groups change differently over time?"
https://statistics.laerd.com/statistical-guides/repeated-measures-anova-statistical-guide.php
Original Message:
Sent: Sat February 25, 2023 03:31 AM
From: Mehlika Ahememulic Ganic
Subject: Repeated measures ANOVA
Hi Rick and thank you so much!
I have made the analyses with three measuring times (pre, post, follow up) and one experiment-group and one control-group.
The problem is that I need to analyse the means, the within-subject effects, between-subjects effect and the interaction effect.
I am not sure how to do that.
And I don´t understand what the interaction-effect is.
I am so confused.
If you could help me understand what I am doing I would be so so happy.
Thank you :)
best regards M
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Mehlika Ahememulic Ganic
Original Message:
Sent: Fri February 24, 2023 03:18 PM
From: Rick Marcantonio
Subject: Repeated measures ANOVA
Hi. I can do it by way of example. Here I have 2 groups, treatment and control, each measured three times: Once before an intervention, and twice after it.
I made up these data:
data list free /pre post_1 post_2 group.
begin data.
15 29 14 0
12 26 15 0
11 28 11 0
13 29 10 0
16 30 11 0
14 28 10 1
14 29 16 1
16 20 15 1
12 22 17 1
17 23 17 1
end data.
variable labels pre "Pre-Test"
post_1 "First Post-Test"
post_2 "Second Post-Test"
group "Control or Treatment Group".
value labels group 0 "Control" 1 "Treatment".
* The "Repeated Measures" model is this...
GLM pre post_1 post_2 BY group
/WSFACTOR=time 3 Polynomial
/PLOT=PROFILE(time*group)
/WSDESIGN=time /DESIGN=group.
------------------------------
Rick Marcantonio
Quality Assurance
IBM
Original Message:
Sent: Fri February 24, 2023 04:40 AM
From: Mehlika Ahememulic Ganic
Subject: Repeated measures ANOVA
Hi I am trying to do a repeated measures ANOVA but I am confused about some things.
I have 3 independent variables (surveys made (with 6 different surveys) at 3 different time periods (before, after and a follow-up after the intervention)).
And I have 2 dependent variables 1 experimental group and one controlgroup.
I want to analyze the within factor, the between factor and the interaction effect.
Could someone guide me in this? I think I have looked at all youtube videos that exists on this...
Have a great day!
best regards M
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Mehlika Ahememulic Ganic
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