i am advise you are read this book

Statistical Analysis with Missing Data(RJA Little, DB Rubin - 2014 - books.google.com)

You can test the hypothesis. Consider "time" as one of the factors in ANOVA.

Hello Ramanjaneyulu Mogili

Thank you for the recommendation.

By the way, I did not have the book. From the book title, it seems more relevant to missing data.

I wonder what is the specific recommended method to be used for my question and what are the assumptions.

Best Wishes

Djamila

Greeting

For my basic knowledge, ANOVA is often used for statistical comparison between the mean of three groups or more.

I wonder, how to to include time via ANOVA to test the hypothesis or to Consider "time" as one of the factors in ANOVA.

I would appreciate very much further information about or receiving a link to a publication so that I understand well the procedure.

Thank You

Best Wishes

Djamila

I was assuming from your question that you had data that were collected at different times. Take a look at the following links that may be helpful:

https://statistics.laerd.com/spss-tutorials/mixed-anova-using-spss-statistics.php

https://www.researchgate.net/post/Two-Way_ANOVA_or_Mixed_ANOVA

Thank You for the Answer and  Useful Links.