Unreliable WiFi on MacBook: how can I measure how "unreliable" it is?
So, how can I measure the quality of a WiFi connection


Use Apple's built in WiFi Diagnostics

Hold the Option (Alt) key while clicking on the WiFi logo on the menu bar.  You'll be presented with two diagnostic options:


Create Diagnostic Report
Open Wireless Diagnostics


The Report is what you're going to want to submit to Apple.

There's an excellent support document, If your Mac doesn't connect to the Internet over Wi-Fi that goes into in depth detail.

You can also get signal quality information via the airport utility and measuring the SNR values via Terminal, but basically, you'll issue the command:

$ airport -I