z test, t test, or chi squared test
 

If I run an AB split test for a marketing campaign and get these results:
A sent: 100000
A success: 50000
A conversion rate: 50.0%
B sent: 101000
B Success: 50400
Conversion rate: 49.9%

Which test would be better to run in order to find out if the results are statistically significant? Also, what results did you get if you ran both or either?

Re: z test, t test, or chi squared test
 

Additional info:

I've used both of the following:

Excel spreadsheet from The Analytical Group (http://www.analyticalgroup.com/download/sigtest.xls) using two independent samples

AB Test Calculator: http://www.splittestcalculator.com/

Not sure if either is right/none are right/both are right (it appears that the analytical group uses z test while the calculator uses Yates' chi squared test)