the failure to replicate

[Michael Sylvester]

what can be the various explanations  why some studies have not
been replicated, or attempts at replication were made with inconsistent
results?
does  the failure to replicate an indication of lack of reliability and 
validity ?
 Can there be such a thing as a one-shot good experiment or research
that no replication or duplication is necessary?

Michael Sylvester
Daytona Beach,Florida