Has anyone ever scientifically tested the significance of a "clean install"?

[Fzang]

With iOS 8 and Yosemite releases and bugs being pushed to users non-stop these days, I see the words "clean install" in pretty much every second comment.

Has anyone ever attempted to scientifically quantify this supposedly "fresh" feeling of removing all your programs and then spend hours to download and set them up again?

 

[iBlazed]

Good question. I haven't done a clean install since 2009. I've been through 4 iPhones since then and have been restoring from backups all these years. Now I'm on iOS 8 on an iPhone 6 and don't have any issues. I'm a skeptic of clean install, I doubt there is any benefit over restoring from a backup.

 

[Roller]

It would be hard to test in a rigorous manner, especially given the essentially infinite range of third-party software that's available. I believe that a clean install is a good way to get rid of old junk, though it's time-consuming. I do it about every second major OS update.

 

[Melrose]

In my experience, it's a noticeable difference in machines going from much older OSs - e.g., Snow Leopard to Mavericks, for example, in my case.

I've done both, and from now on will do only clean installs just for peace of mind later. it does make a difference.