What attribute values should I look for in my X-Com Troopers?

Playing X-Com Enemy Unknown, and I have a Heavy with a 30 Will who panics at the drop of a hat, so I know I should probably trash him.

Obviously I want troops with high attribute value, but what numerical attribute values should I be looking for in recruits to decide whether to keep or ditch them?

Also, how is this decision affected by changes from the Second Wave patch?

All rookie soldiers start with 40 Will and gain Will increases as they gain ranks. They suffer a decrease in Will when they suffer a critical wound in battle. Therefore, there isn't really a single low number to worry about, as it varies by each rank. Also, a Squaddie (or any other low ranked soldier) who has been critically wounded can eventually gain enough Will back to be a successful soldier.

The table below shows the low and high Will values a soldier can have, by rank. By checking each soldier against the table, you can determine if their will is too low for the rank they have. I've included the low and high Will values for when the Iron Will upgrade has been purchased. However, I'm not certain how helpful those will be, as you generally purchase that upgrade after your soldiers have been promoted a few times, so you won't expect to see values as high as the columns indicate.

I created the table using the following assumptions:

• Each soldier gets a fixed +2 per level.
• Each soldier gets a random +1d6 per level (iRandWillIncrease=6 in the ini file).
• Each soldier gets another fixed +2 per level when the Iron Will upgrade is purchased (iBaseOTSWillIncrease=2 in the ini file).
• Each soldier gets another random +1d4 per level when the Iron Will upgrade is purchased (iRandOTSWillIncrease=4 in the ini file).

(See http://wiki.tesnexus.com/index.php/XCOM:EU_DefaultGameCore.ini_settings for the ini values.)

                        Iron Will
Rank        L   H       L   H
Rookie      40  40      40  40
Squaddie    43  48      46  54
Corporal    46  56      52  68 
Sergeant    49  64      58  82 
Lieutenant  52  72      64  96 
Captain     55  80      70  110 
Major       58  88      76  124 
Colonel     61  96      82  138

The Second Wave options Not Created Equally and Hidden Potential change all of this. Not Created Equally changes the starting Will from a fixed 40 to a random number between 25-60. Will increases stay the same. Hidden Potential changes the Will increases (and all other stat increases) to be random, so there will be a much larger variation of Will values among your soldiers. The above table can still be used to check whether you have a soldier who is better or worse than "normal", though.

There are four attributes: AIM, Defense, WILL, and Mobility.

Defense and Mobility are the same for all soldiers, and so do not need to be considered.

WILL is used two places. Panic checks and psionic attacks/defense. A high WILL stat allows you to panic less frequently, resist psionic attacks and hit more frequently with psionic attacks.

WILL values start randomly and increase random amounts with ranks. The rank up amount is higher once Iron Will is purchased. Checks involving WILL are modified by PSI Armor and Mind Shield.

AIM is used to determine a gun attack's chance to hit. If you press F1 while you have an enemy targetted during an attack, the chance to hit will be displayed. The base chance is exactly your AIM score : 65 AIM = 65% base chance to hit. Items which improve AIM checks include Scope and Light Plasma Rifle, as well as pistols with Improved Pistol II.

AIM values are the same for all rookies by default. AIM increases with ranks at a rate determined by the soldier's class. Snipers have the highest AIM, followed by Assault and Support (tied), with Heavy having the lowest AIM.

Heavy's low AIM is not as big of a liability as it sounds. Heavy should usually spend the turn firing twice (compensating for low AIM), suppressing or launching rockets (actions which do not require AIM).