3 ms·

That is not the reason it is junk. Typically the reason to call something junk is that designing the study itself is difficult, not sample size. There are analy

That is not the reason it is junk. Typically the reason to call something junk is that designing the study itself is difficult, not sample size. There are analysis of small to large groups to determine how small a group can be that will still reflect the whole. 9 does seem on low end, but I think the typically accepted size is something in the 20's of individuals. I'm guessing that if 9 is enough to call it junk, then 20 would not sway your opinion. What is a good number then? 100? 1000?. Guess could do identical study on groups of 10,100,1000, and show that the results replicate across the size. Of course, this has been done, hence why they get away with smaller sizes.

suslik 3y ago
This isn't a guessing game, really. You have some prior knowledge of the expected effect size - that allows you to calculate the sample size required for your statistical test to have a certain power. That is an essential and very simple part of a good experimental design which, unfortunately, is very often ignored.
p-e-w 3y ago
There is no fixed size of samples that guarantees a result is statistically significant. How many samples are needed depends on the desired p-value among other things, which in turn depends on prior assumptions, and on the quantities being measured. "Typically accepted sizes" are nothing but cargo cult science. That's precisely why psychologists take statistics classes as part of their education. I get that those aren't everyone's cup of tea, but people who don't even understand the basics have no business conducting and publishing studies. In fact, well-designed scientific studies typically start with a discussion of p-values, sample sizes, possible sources of biases, etc. If you don't see any mention of those in a study, you know you're looking at junk.

3 ms·

That is not the reason it is junk. Typically the reason to call something junk is that designing the study itself is difficult, not sample size. There are analy

by FrustratedMonky 3y ago

suslik 3y ago
This isn't a guessing game, really. You have some prior knowledge of the expected effect size - that allows you to calculate the sample size required for your statistical test to have a certain power. That is an essential and very simple part of a good experimental design which, unfortunately, is very often ignored.
p-e-w 3y ago
There is no fixed size of samples that guarantees a result is statistically significant. How many samples are needed depends on the desired p-value among other things, which in turn depends on prior assumptions, and on the quantities being measured. "Typically accepted sizes" are nothing but cargo cult science. That's precisely why psychologists take statistics classes as part of their education. I get that those aren't everyone's cup of tea, but people who don't even understand the basics have no business conducting and publishing studies. In fact, well-designed scientific studies typically start with a discussion of p-values, sample sizes, possible sources of biases, etc. If you don't see any mention of those in a study, you know you're looking at junk.