3.1 Between Groups Designs
You have 2 groups and you want to see the differences between them.
3.2 Within Group Designs
You have just 1 group and you want to see the differences within that group itself.
# Elements of Research Design:
|4| One time vs. over time research
4.1 Cross-sectional method
The risk here is : you don't get the reality , you don't get the real finding because the 2 groups are different .
4.2 Longitudinal method
The risk here is : the attrition of sample "تآكل او النقصان في عناصر المجموعه "
ex: maybe now you have 111 children but after 3 years you don't have the same number…