Experiments that are literal replications of previously published experiments are very seldom published—I do not believe I have ever seen one. Others who have done systematic searches for examples of them confirm that they are rare (Mahoney, 1976; Sterling, 1959)....PhD committees generally expect more from dissertations than the replication of someone else’s findings. Evidence suggests that manuscripts that report only replication experiments are likely to get negative reactions from journal reviewers and editors alike (Neuliep & Crandall, 1990, 1993)
I wouldn’t. Two studies opens the door to publication bias concerns
Agreed. It’s much easier for a false effect to garner two ‘statistically significant’ studies with p < .05 than to gain one statistically significant study with p < .005 (though you really want p < .0001).
I wouldn’t. Two studies opens the door to publication bias concerns and muddles the ‘replication’: rarely do people do a straight replication.
If you put the general significance standard at P<0.005 you will even further decrease the amount of straight replications. We need more straight replication instead of less.
A single study can wrong due to systematic bias. One researcher could engage in fraud and therefore get a P<0.005 result. He could also simply be bad at blinding his subjects properly.
There are many possible ways to get a P<0.005 result by messing up the underlying science in a way that you can’t see by reading a paper.
Having a second researcher reproduce the effects is vital to know that the first result is not due to some error in the experiment setup of the first study.
I wouldn’t. Two studies opens the door to publication bias concerns and muddles the ‘replication’: rarely do people do a straight replication.
From Nickerson in http://lesswrong.com/lw/g13/against_nhst/
Agreed. It’s much easier for a false effect to garner two ‘statistically significant’ studies with p < .05 than to gain one statistically significant study with p < .005 (though you really want p < .0001).
If you put the general significance standard at P<0.005 you will even further decrease the amount of straight replications. We need more straight replication instead of less.
A single study can wrong due to systematic bias. One researcher could engage in fraud and therefore get a P<0.005 result. He could also simply be bad at blinding his subjects properly. There are many possible ways to get a P<0.005 result by messing up the underlying science in a way that you can’t see by reading a paper.
Having a second researcher reproduce the effects is vital to know that the first result is not due to some error in the experiment setup of the first study.