Subject: What are the factors that cause a nonmoving incand. light bulb to burn out?

I am conducting a science fair experiment with light bulbs. One part of my 
experiment is observing 2 clear glass light bulbs and 2 soft white light 
bulbs (all 60 watt) and seeing if one type burns out sooner than the other. 
The second part of my experiment is measuring the resistance of each type 
over a period of time to see if there is a difference in how fast the 
resistance changes.
What education and experiences do you have that lend itself to this type of 
information?
Do you know of the length of a regular 60 watt bulb can live? What affects 
this? I think that a clear bulb would last longer than a soft white bulb 
because I think the "tint" or "glaze" on the soft white bulb would trap 
more heat causing the filament to evaporate faster than the clear bulb.-Is 
that a logical assumption?
Do you know if the  electrical resistance of a clear bulb differs from the 
resistance of a soft whit bulb?-Over time does one drop faster than the 
other?

Re: What are the factors that cause a nonmoving incand. light bulb to burn out?