s******y
发帖数: 522 | 1 要做一个关于老年人的课题，但现有的数据库是对于全部年龄群的采样
如果从中把所有的老年人样本删选出来，这样还是randomized的吗 |
O*****y
发帖数: 222 | 2 我认为是
【在 s******y 的大作中提到】
: 要做一个关于老年人的课题，但现有的数据库是对于全部年龄群的采样
: 如果从中把所有的老年人样本删选出来，这样还是randomized的吗
|
j*****e
发帖数: 182 | 3 How did you sample from the pop with all ages?
What about the sample size of elderly?
Randomized means iid. Are subjects iid here? |
s*r
发帖数: 2757 | 4 randomized is not the same as random |
a***r
发帖数: 420 | 5 我觉得你想说的是sample是不是randomly recruited的？
如果是这样的话，我觉得算是
前提是数据库采样的recruitment是non-biased的,在比如性别，种族，等等你想“
randomize”的因素上分布是“random”的
然后仅仅根据年龄筛选“老年人”
【在 s******y 的大作中提到】
: 要做一个关于老年人的课题，但现有的数据库是对于全部年龄群的采样
: 如果从中把所有的老年人样本删选出来，这样还是randomized的吗
|
p***r
发帖数: 920 | 6 there is no sample is randomized, every sample is fixed, after you stick
with a design. |
l*******n
发帖数: 19 | 7 "Random sample" and "Randomized design" are different concepts.
If there is no treatment intervention, you have an observational study.
Your samples (no matter old or not) are still random.
If there is treatment intervention, the subgroup design (old people) may
not be randomized even your overall design is randomized, when your design
was not stratified by age (with old as a stratum).
【在 s******y 的大作中提到】
: 要做一个关于老年人的课题，但现有的数据库是对于全部年龄群的采样
: 如果从中把所有的老年人样本删选出来，这样还是randomized的吗
|
j*****e
发帖数: 182 | 8 It seems like superray used the wrong terminology in his question. There is
no randomized sample. However, there is random sample, which most stat
analysis developed for.
It is hard to collect a random sample, since the population is not naturally
stratified by age here.
Assume they collected their original sample randomly,
you can view what they did as a two-stage sample. In stage one, you take a
random sample from the population. In stage two, you stratify stage one
sample by age and either ta |
