Thank you for repeating this.
While doing the study, I noted that the IV increase might only occur to the front month contract, and not even to the next month.
Take the case of Sears SHLD, it has delayed the announcement of earning recently. On 8 Nov, the company announced that the earning announcement will be made on 16 Nov, the IV of the front month Nov contract went 10+ point to 46% (ATM) and not so much on the next month Dec contract (33%).
Going toward the earning announcement, on 13 Nov, the IV of front month NOv contract went up to 72 % (ATM) and the Dec contract only increased by 3 points (36%). Please see the attached option price chain for some detail.

This behaviour should be quite common on other counters as well. Managed to look at AAPL. In the last earning announcement, AAPL made announcement on 18 Oct 2006 :
Market close on 11 Oct 2006, AAPL at $73.13
Oct 80 Call QAAJP at $0.7 IV=60.9%
Nov 80 Call QAAKP at $1.75 IV=43.5%
Market close on 17 Oct 2006 at $74.35
Oct 80 Call QAAJP at $0.45 IV=79.3%
Nov 80 Call QAAKP at $1.725 IV=42.5%
So the IV increase is most likely on the front month, it might or might not increase that siginificantly on the next month or back month contract.
While doing the study, I noted that the IV increase might only occur to the front month contract, and not even to the next month.
Take the case of Sears SHLD, it has delayed the announcement of earning recently. On 8 Nov, the company announced that the earning announcement will be made on 16 Nov, the IV of the front month Nov contract went 10+ point to 46% (ATM) and not so much on the next month Dec contract (33%).
Going toward the earning announcement, on 13 Nov, the IV of front month NOv contract went up to 72 % (ATM) and the Dec contract only increased by 3 points (36%). Please see the attached option price chain for some detail.

This behaviour should be quite common on other counters as well. Managed to look at AAPL. In the last earning announcement, AAPL made announcement on 18 Oct 2006 :
Market close on 11 Oct 2006, AAPL at $73.13
Oct 80 Call QAAJP at $0.7 IV=60.9%
Nov 80 Call QAAKP at $1.75 IV=43.5%
Market close on 17 Oct 2006 at $74.35
Oct 80 Call QAAJP at $0.45 IV=79.3%
Nov 80 Call QAAKP at $1.725 IV=42.5%
So the IV increase is most likely on the front month, it might or might not increase that siginificantly on the next month or back month contract.
Quote from optioncoach:
If you know for a fact that the earnings will be in JAN expiration then that is the month you want to be long. I chose APR to give me more time to play the directional side and to push up my vegas so even smaller moves in IV will help the position.
When DEC expires, I can still add JAN positions to take advantage of IV spike. Whether short or long, you can use the IV spike to your advantage.
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