Monday, 10 January 2011

An ability score of 3 is unplayable (Argument 2a)

[Drum roll]            More Statistics and the Strength ability score

So let’s recap for a moment where we are with this topic.

Argument 1 – Using the ability score of intelligence as presented in the rules I argued that an Intelligence Score of 3 (was one step more intelligent than a dog – Intelligence 2). Additionally I argued that EGG strongly implied that your IQ divided by 10 was equal to your intelligence score. Therefore an Intelligence Score of 3 = IQ 30, which is severely mentally handicapped. 
Argument 1a – I supported Argument 1 by exploring the spell Feeblemind, which lowers a spell casters intelligence score (AD&D Moronic child, Intelligence score 5-7; B/X & Mentzer idiot, Intelligence score 2), which Mentzer describes as ‘helpless’.
Argument 2 – Comparing bell curves to a normal distribution (as is often done with the Intelligence score) and drawing on an excellent external post by Daniel Collins, I argued that applying a normal distribution to a 3-18 ability score is poor statistics and distorts ability scores at the extremes. If used on the Intelligence score, it makes clever people regard themselves as geniuses. If such poor statistics were applied to low Intelligence scores than an Intelligence score of 3 would be even worse than it is usually considered.       

My conclusion to date:
Reroll, readd, redo - An ability score of 3 is unplayable

Brains ready… here’s some more statistics! If you hold out it gets more interesting further below when I get to strength.

Disclaimer: Please I’m not a statistician, though I have taught statistics. To a statistician everything I say is likely to be over-simplified and not 100% true, but I think my general thrust is correct.

I wonder what Delta thinks?

Let’s look at how data can be categorized.

Data Type
Description
Examples
Categorical
Data is in a category, the category has no rank, in that no category is better than another
Male/Female
D&D class or race
D&D alignment
Ordinal
Data is in categories, sometimes has a number or letter and the categories/number/letter have an order or a rank. However the gap between each rank or number is not equal (or what each rank represents is not the same step between each rank).
1st, 2nd and 3rd in a race (1st is not twice as good or fast as 2nd)
IQ (see below)
D&D Treasure Tables (Category A is not twice as good as category B, sort of true but the order is chaotic)
D&D spell levels (a level 3 spell is not clearly three times as dangerous as a level 1 spell, you know it’s better but you can’t know by how much)
D&D level (since a different XP is required for each level, level 4 is not four times better than level 1. We know it is better but can’t say by how much)
D&D Ability scores (see below)
Numerical (Discrete / Interval)
Data is a number, the gap (interval) between each number is the same, but there is no zero (without a zero one cannot say that one number is twice or half another number)
Temperature in Fahrenheit or Celsius (50 F is not half of 100 F – it’s not trust me; were we talking in Kelvin which has an absolute zero minus 273Celsius, than 100K is twice 50K)
D&D Armor class (an AC of 2 is not twice as hard to hit as AC 4, but each step between AC 2,3,4 is equal on the monster ‘to hit’ chart anyway)

Continuous (Ratio)
Data is a number, the gap between each number is the same, and there is a zero (so one can easily say something is half of something else - ratio). Often is normally distributed in the population for human and natural biometric values.
Height, weight (all can be zero)
D&D hit points, encumbrance, movement, experience points

Right got that?

Let’s pick up two ordinal values: IQ and ability scores.

Interestingly and perhaps surprisingly IQ is ordinal and not numerical or continuous, yet often it is treated, even in psychosocial literature, as being a normally distributed continuous variable. This is because the IQ test is a man made test that ranks people into categories depending on their result (ordinal). In the same way if someone got twice as much in an exam as you it is wrong to say they are twice as smart, they may be but the test doesn’t tell you that. IQ is not a measurement in the true sense of the word and an IQ of 120 is not twice as smart as 60, it is likely to be much more in fact. Even the gap in intelligence between 100 to 120 is not necessarily the same as the gap between 80 and 100 (so not numerical).
For further information or explanation see

Ability scores
When one looks at the below B/X table
Ability Score
Adjustments
3
-3
4-5
-2
6-8
-1
9-12
0
13-15
+1
16-17
+2
18
+3

The table looks so symmetrical it must be numerical.
But the gap or effect between 16 and 12 (+2) is not the same as 12 and 8 (-1). There is order 16 better than 12 better than 8, but one can’t say that 16 is twice as strong, smart, good looking as 8. The data is therefore ordinal.

This is even more apparent if one looks at retainers for Charisma (3 – 1 retainer, 18 - 7 retainers), Intelligence (3 – trouble speaking to 18 - +3 languages), XP adjustments (3 – 20%, 18 - +10%).

So what’s my point?

I think people often play D&D as if 3 is only half as bad as 6 or 3 times worse than 9. That is a 3 ain’t that bad. For intelligence score I think I have convincingly shown in my previous postings why this is not the case - 3 is awful, 3 is unplayable. But the other ability scores are more problematic. The way the ability scores are in the table above -3 to hit and damage is a disadvantage but not unplayable. Let’s think carefully here, it’s only a minus 15% chance to hit! You could live with that.

Or could you?

The ability score of Strength

In my first posting on this topic I said, "Intelligence is the only ability score that is related in the rules to a real life comparator." Spawn of Endra pointed out something I had overlooked in the Players Handbook (page 9). Strength of 3 = the ability to military press a maximum of 30 pounds, 18 strength, 180 pounds. (From the above that would make it a continuous variable, since at zero strength one could lift zero pounds and 18 strength is six times more than 3 and can also lift six times as much)

So like intelligence EGG identifies a real life comparator for strength that is divisible by 10 into an ability score. What a shame there is nothing for wisdom, dexterity, constitution (breath holding, fitness, colds per year perhaps) and charisma.

I must say researching strength has been very interesting if a little frustrating.  Interesting because if you thought we were an obsessive bunch of bloggers or had one up man ship dominating our hobby, you should see the body builder forums and blogs. Frustrating because what I really wanted to find was a normative table for the military press – I never found one.

The dreaded military press was properly performed standing, with legs unbent, and the weight lifted above ones head. It was military because it was used to test strength to get into the military and was once considered the preeminent test of strength. So why can’t I find a table!

Let’s look at maximum 30 pounds, strength 3.
This is very weak.
The bar for weightlifting (Olympic standard) for men is 44 pounds, women 33 pounds.

So at strength 3 one cannot even lift over your head the bar, without any weights.

I would love to know what a child could do and how this compares. I don’t have any weights at home (hey I’m a nerd, hence this blog). I tried getting my four year old son and six year old daughter to lift some random objects over their head (carefully!). They had trouble holding the objects more than the weight so the experiment broke down. My daughter can lift her uncle who is about 65kg momentarily off the ground (feet together arms around waist). I’m 75kg and she can’t lift me.  So I wonder if she could manage 30 pounds weight over her head.

Now the military press is notoriously harder than other weight lifting, so maybe she couldn’t. Let’s assume for the sake of this argument she could, or maybe an eight year old could. Anyone got gym gear, a child and a tolerant wife to test this theory? Are we saying that an eight year old who we are assigning a strength of 3, would this eight year old in combat with a monster be only -15% to hit compared to the average man, and do a minimum of 1 damage, which in two hits would start killing normal men and women? I find this hard to believe.

Now D&D doesn’t have to be realistic but it does have to be internally consistent. Let's ask it again - Can someone who can only lift 30 pounds over their head really only be -15% to hit compared to the average man and do a minimum of 1 damage, which in two hits would start killing normal men?

No, I don’t think so.

I perceive there is internal illogic. The desire for symmetry in B/X ability scores is leading to some strange conclusions. AD&D has less symmetry (18 strength +1 to hit,+2 damage; 3 strength -3 to hit, -1 damage) but does not fare much better. Can only lift 30 pounds but weight allowance for encumbrance is only -350 pounds compared to normal.

Also I don’t think EGG is correct in relating strength to real life military press.

You see with Intelligence the natural human range is 0-228 (Marilyn Vos Savant)
Einstein 160, Stephen Hawking 160, Bobby Fischer 187

I don’t care how accurate or inaccurate these numbers are, the point is that on a D&D 0-25 score system (3-18 for most of the D&D world), in encapsulates the breadth of mankind and even extremes above and below mankind, to account for gods etc.

The military press world record: the heaviest recorded military press was 535lbs ,242.67 kgs, and was set by Dj maestro. http://wiki.answers.com/Q/What_is_the_heaviest_military_press

According to EGG that’s a strength of 53, twice as strong as the strongest god.

There’s a club for the over 300 pound overhead press.

Yet a body building enthusiast confesses to lifting only 85 pounds in the military press and the responses aren’t much better.

This enthusiast 105 pounds
So hardly 100 pounds = average, if that’s all these enthusiasts can manage unless they are role players after their gym sessions.

One 13 year old says he can do 165 pounds.

Someone else says:
“A human being who has Athletic physical strength can military press the weight of the average human being or greater; roughly 175 lb (80 kg). In the real world, the vast majority of the population isn't capable of military pressing 175 pounds or more.” He then gets shot down by other commentators.

This for the strongest warrior comepetition.
Competitor 135lb Men/65lb women for this event.

I have no idea what the truth is and don't really care. But the randomness for the military press and the range seems huge, though I think the techniques aren’t clearly defined between these reported weights. So it's use as a comparator to D&D strength seems wildly implausible.

From my research I actually think grip strength is a better comparator to D&D strength. I’ll post that another day.

So bringing today’s ramble to a close.
Ability scores, as ordinal data, do not have to be symmetrical in their pluses and minuses, just ordered. Symmetry leads to confusion and the belief that 3, ain’t that bad. It is.
The rules regarding strength are confusing and inconsistent. -15% to hit with strength 3 is not consistent with the inability to lift more than 30 pounds over your head. You are likely much worse and much more debilitated as an adventurer.

Reroll, readd, redo - An ability score of 3 is unplayable

Wednesday, 5 January 2011

Weapon breakage, shields sundering and armor survival

As much as I am enjoying blogging about ability scores, I have a KotB campaign to run and the first session, Feb 5th, is only a month away.

So a momentary pause as I collect some house rules into one place. Now these aren’t original, though I have tweaked them to my liking, and I have linked to the inspired creators original blog posting where I can.

Weapon Breakage
Alexis at Tao of D&D has some excellent ideas about weapon breakage. Then he rants against one of his commentators, and undo’s some of my admiration, not that Alexis would care what I think.

His motivation in his post was to save the battle axe. I don’t feel the same need as I have already done, in my opinion, much to redeem the battle axe for my campaign; class-based weapon damage and axes equally good against both metal and non-metal armor compared to swords.

Alexis applies a weapon breakage rule on a natural roll of 1, what others house rule as a critical fumble (as did Alexis initially) and I proposed would lead to a minus 1 on initiative for the WHOLE PARTY in the next round.

I am now abandoning the initiative penalty, though possibly may reintroduce it in the future in addition to the below proposal. Because there is something very attractive about weapon breakage. It adds drama, it is realistic as weapons certainly do break, it allows for differing qualities of weapons to have different break points, it encourages new weapon experimentation when a weapon breaks and it removes magic weapons from the party’s arsenal and keeps them acquisitive and hungry for more.

Yes you heard it – it removes magic weapons. As a DM, you have to like that.

The devil as always is in the detail.

Alexis proposed a system where breakage occurred on:
1in 6 - ordinary, crummy weapon
1in 8 - 'hard-forged' weapon
1 in 12 - 'blessed' weapon, one that had been hard-forged and both lucky and loved in its construction
1 in 20 - 'mastercrafted' weapon would be the kind made by an artist or a magic weapon

All great stuff but I wonder what happened to 1 in 10, I think Alexis wanted to step up quickly from ‘hard-forged’ to ‘blessed’.

I have been thinking about magic weapons and non-magical weapons of quality weapons for my campaign. I want to keep magical weapons, magical. I discuss my campaign ideas much further below.

What I really like about Alexis’s weapon breakage system is it makes weapons special even when they aren’t magical.

What I am planning to use:

On a natural roll of 1 on a d20 ‘to hit’ roll a 2nd dice must be rolled to see if the weapon breaks, using the following table.

Dice
Weapon Quality
notes
1 in 6
Cheap, poor
Less than full cost
1 in 8
Ordinary
Full cost (ordinary long sword 15gp)
1 in 10
Well made / quality
x3-x10 cost (well made long sword 45-150gp)
1 in 12
Superb / masterful
x100 cost (masterful long sword 1500gp)
1 in 20
Magical, elven or dwarven make
>x100 cost (magical long sword 2000gp as per DMG). Most magical weapons prior to enchantment will be as a base a masterful weapon.
1 in 20 twice in a row and so forth
If higher categories are desired (eg per additional + of the magic item)
Perhaps the magic weapon losing +1 each time it ‘breaks’ whereupon if it breaks again when non-magical it is broken for good, unless reforged / remade.

Missile weapons:
Bows – 1 in 6 breakage is of the string, 6 turns to repair if spares carried (total destruction see below)
XBow – 1 in 6 breakage is of the mechanism, need weapon maker to repair (total destruction see below)
Sling, other natural product – as per above table and the item is irreparable

Now detractors might think, how can a well-made weapon break every 200 swings (1 in 20 then 1 in 10= 1 in 200).
Combat is abstract so we are not counting swings and I assume the swings occur even more often in weapons practice. What we are looking at is the chance for the weapon to fail when it’s needed the most.

It may not be totally realistic but it looks like damn good fun for players and DM alike.

Shield Sundering
Trollsymth has a legendary post about shields sundering / splintering and I urge you to click on the link if you haven’t read it.

My take is this:
As a desperate last-ditch defence to avoid a likely mortal wound, shields, and only shields, may be sundered.

BEFORE damage is rolled but after a successful hit a character armed with a shield may elect to sacrifice the shield to avoid the damage. No damage is rolled for or applied and the shield is considered destroyed (sundered) and must be immediately discarded. Likewise against a breath attack or some other damage causing spell that may be minimized by a saving throw, BEFORE the saving throw is made, the shield can be sundered and the character automatically makes their save.

Magic shields (but not shields of quality or superb, which are both still normal shields) will lose +1 for each time they are sundered and are destroyed once they are sundered a final time as a normal shield.

Cursed shields cannot be sundered; instead if sundering is attempted, the character will take maximum damage from the attack or automatically fail the saving throw, whichever is more appropriate, reflecting the curse having it’s full effect.


Armor and missile weapon survival (bows and crossbows only)
When a character or NPC/monster is killed OR reduced to zero or below hit points the armor and any bows or crossbows plus any other potentially fragile items must make a save vs magic wands using the owners Hit Dice/Level, or be destroyed / rendered useless. Magic armor or bows/crossbows (but not items of quality or superb, which are both normal items) will get their bonus applied to the save but lose +1 for each time they fail their save and are destroyed once they fail a final time as a normal item.

This method means that dead heroes (better saves) are more likely found with armor intact and follows DMG rules for item saves more closely (see DMG page 80) but doesn't use the DMG complicated table. It can also be applied when the party wants to know if they can use the dead orc's or companion's armor.

That’s enough about rules, let’s talk KotB in my campaign world.
Magic items are going to look like this:
Most +1 magic items found in B2:KotB module are instead going to be items of quality and not magical. They cost a minimum of 3x more than a regular item. I may on some special items give them a +1 ‘to hit’ bonus but not also +1 to damage and therefore they cannot damage magic creatures requiring a +1 magic weapon or better to hit. They simply have no effect on these creatures. Quality weapons and also quality shields and armor are as heavy as the normal variety. Hopefully this framework allows me more freedom in the creation of items I give to the party without resorting to powerful magic so early in the campaign. A weapon that breaks less, is worth more gold and perhaps has a +1 'to hit' bonus is pretty special for 1st or 2nd level.

Elven crafted magic Items
The majority of magic items are of elven make, but are still very rare.  They can be +1 or better and can damage magic creatures, providing they are powerful enough, as stated in the monster description.

Dwarven forged magic items are made by dwarves for dwarves but can be used by other specifies if their size allows. Very very rarely dwarves have made items suitable for use by other species.

Magic-User enchanted magic items – can be of any power and after elven magic items are the next most common.

Clerical magic items or sacred items are of two types. (you will need to look at this post to understand this section)
For similar time and costs a high level cleric may make an item that will be blessed by Law or a Chaotic Minion to imbue the item with magical strength. Normally the item will contain, somewhere in its construction, a relic of a famous martyr or minion and the gaining of such a relic will usually involve a difficult quest.

Incredibly rarely Law may bless an item on the battlefield for use by a Lawful Character creating either a temporary magic item for that battle or even more miraculously a permanent one. Chaos just does not care for its’ minions in the same way Law does. The blessed item will never be one that is already magical but if this miracle occurs it will be on a mundane weapon or item picked up on the battlefield by a beleaguered martyr. For example having been disarmed the martyr breaks off a tree branch to use as a club or else picks up a fallen soldiers normal spear, and miraculously finds the weapon blessed. A guide for the chance of this miracle occurring can be that when death appears certain for a Lawful cleric (other Lawful characters are at half chance) there is a base 1% chance per level of this miracle occurring, modified by the DM for the circumstances. The chance of the item being permanently magical should be the same percentage chance rolled again. For a lawful character less than 10th level the item will be +1, 10-19th level +2, 21st level and above +3; the item may have other special abilities at DM discretion.



That’s it for the moment. A final note.


I have found some interesting articles on grip strength and norms in children and all adult ages – quite relevant for my research on ability scores and strength. I can not find norm references for the military press, remembering (thanks to Spawn of Endra for reminding me) that DMG says strength 3 is the ability to military press 30 pounds, 18 strength 180 pounds. If anyone can find some norm referenced tables for children and adults of different ages for the military press, I would be very grateful.

Thanks for reading

Tuesday, 4 January 2011

An ability score of 3 is unplayable (Argument 2)


[Drum roll]            Statistics

Bell curves
As we all learnt in the DMG (page 10) 3d6 creates a curve and calls it a bell curve. But this curve is not normally distributed and is therefore not a true bell curve as often suggested or used inappropriately.

Look at the comparison of the two different curves below:
3d6 probability in red and a normal distribution bell curve in green (apologies as hard to see somewhat)

Image from:http://nethack.wikia.com/wiki/File:3d6.svg

http://www.netmba.com/statistics/distribution/normal/ gives a good summary of Bell Curve Characteristics and I’ll Compare them to the 3d6 curve above:
Symmetric [Yes]
Unimodal [Yes]
Extends to +/- infinity [NO]
Area under the curve = 1 [Yes, since all values of 3d6 are under the curve, unless one allows race and age adjustments beyond 3-18, when the answer would be NO]

So close, but no banana.


The Empirical Rule for a normal distribution bell curve is:
68% of the data will fall within 1 standard deviation of the mean
95% of the data will fall within 2 standard deviations of the mean
Almost all (99.7%) of the data will fall within 3 standard deviations of the mean

Torben, at the Troll Dice Roller, has an excellent little free on-line program to calculate probabilites. (He’s very helpful by the way and sent me the code for 3d6 reroll 1’s when I emailed him, which is: “sum 3#(repeat x:=d6 until x>1)”.)
Anyway the probability for 3d6 and capturing his screen shot is:

The spread or standard deviation (SD) for 3d6 is 2.958 (or 3 amongst friends) from a mean of 10.5.
1 SD around the mean is 7.5 – 13.5, which has only 60.6% of values compared to normal distribution 68%
2SD 4.5-16.5, 97.7% vs 95%
3SD 1.5 – 19.5

That is, it looks exactly like the red curve at the top of this post but shorter and plumper, with less tail than a normal distribution.

Since as stated above, almost all values will lie within 3 standard deviations of the mean and since one can’t generate on a 3d6 ability scores of 1,2 and 19, 20 the point that a 3d6 curve is not normally distributed becomes obvious.
So what? Daniel Collin’s essay on this whole IQ, Intelligence score and bell curve topic is well worth reading. One argument he makes is why should our fantasy world follow the same rules for normal distribution as our real world. Very true and difficult to argue that one.

He also says the following and I’ll quote a large chunk but please hit the link to read the rest:
“One of the most popular alternate theories by D&D gamers who are unaware of this history is to theorize that they should "compare the bell curves". That is, they contend that one should calculate a relation by considering what percentage of real-world people have a certain IQ range (constructed specifically with a 100 mean, and standard deviation of 16), and map that to a range of equal percentage likelihood when rolling 3 six-sided dice (range of 3-18, with a 10.5 mean, and standard deviation of 2.95). The end result is a formula such as Int = (IQ – 100) / 16 * 2.95 + 10.5.
A relation like this has the effect of scaling the extremes of IQ scores further out on the Int scale. This presents several practical problems: (1) animal-level intelligence would correspond to Int 1 = IQ 48 or Int 2 = IQ 53, which would be high enough to learn language; (2) the minimum for humans, Int 3 = IQ 60, is sufficiently high as to entirely miss several categories of real-world intelligence deficiencies (see below); and (3) the maximum for humans, Int 18 = IQ 141, is actually far below the results for some real-world people on standardized IQ tests.
The best example of this last problem is the Guinness record-holder for Highest IQ, Marilyn vos Savant, who reportedly has an IQ score of 228 (subject to some debate; see links at end). Under the "compare the bell curves" theory, this would translate to Int 34, which is wildly beyond the range possible in D&D by rolling 3d6 (in fact, beyond the range of most gods in D&D). Even if we are skeptical of this IQ score, considering the previous record holder’s IQ of 196 results in Int 28, again far beyond the 3-18 result achievable in D&D. In contrast, the simpler linear relation properly brings these scores into the more reasonable range of 19 and 22, which is in fact naturally achievable in D&D via several methods. (E.g., a roll of 18 plus a few age or level-based ability bonuses, reasonable point buy, etc. The "compare the bell curves" method is not remotely correctable even by maximizing such increases.)
One amusing "advantage" of the scaled curve system is that it strokes D&D players’ egos by making them look extremely smart in game terms. I’ve seen multiple online discussions of this topic in which everyone participating gleefully points out that their IQ scores translate to a D&D Intelligence of 18 or more under this model, and feel that that’s entirely reasonable.”

Thanks Daniel, back to me:
So bell curving D&D ability scores is poor stats. If we are going back to intelligence it tells us two things, we don’t all have IQ of 18. Embarrassingly, I once used my state-wide education academic record that said I graduated in the top 1% to conclude, ah-hem, I had an intelligence of 17 - 18, so I was very guilty of the poor thinking Daniel is criticising. I would estimate 11-12 now (IQ 110-120), and I’m considered clever. What this should tell us about low Intelligence scores is that an Intelligence score of 3 is really, really bad. If strength, wisdom, dexterity, constitution and charisma in any way mirror intelligence, then the same should apply. More on other ability scores in the next post.

But first a way out:
While not completely necessary for my argument this is a useful link on IQ and standard deviation. I could, at a pinch support the fudge (very bottom answer – ‘compressed IQ to 10 points per INT past 1 std dev’), that redefines IQ to not be as bad or good at the extremes – therefore a playable ability in the 3-18 range.

However this would not support Argument 1 (first post) where I showed the rules clearly relate Intelligence score of 3 to IQ 30, which is unplayable. So either way one is house ruling. You can’t have a playable character with IQ 30 and must reject it (breaking the rules that say 3-18 is playable), or one is forced to accept a new distribution of IQ that was never suggested or supported in the rules. You choose?

I know my choice...
Reroll, readd, redo - An ability score of 3 is unplayable

PS I need to thank Spawn of Endra. In my first posting on this topic I said, "Intelligence is the only ability score that is related in the rules to a real life comparator." Spawn of Endra pointed out something I had overlooked in the Players Handbook. Strength of 3 = the ability to bench press 30 pounds, 18 strength, 180 pounds. This needs more to be said, and I hope to get to other ability scores soon, as promised.

PPS I also wish to welcome my two new followers, Old School Psionic and Galpy of 15mm Paint Shack 

Sunday, 2 January 2011

An ability score of 3 is unplayable (Argument 1a)

In response to the comments from my previous post, I want to repeat the clarification I made there. I do not doubt there are ability scores of 3 in a campaign world. My belief is that were they to be role-played appropriately as per the detrimental effect of that ability score - it would be no fun as a player and not allow adventuring as the game rules are intended. For this reason an ability score of 3, and in my opinion also of 4 and 5, are not legitimate choices for PCs; they exist only for NPCs or temporary magical effects for PCs. In character creation, were a PC to have an ability score of 3, then the correct action of the DM is to choose a method to increase that score (raise it to 6, ask PC to re-roll entire character, re-roll that ability only, create characters using 3d6 reroll all 1s, etc).

Argument 1a 
I was going to launch into statistics for Argument 2 but first, as an interlude, I give you Argument 1a: the spell Feeblemind. To understand the spell I need to repeat this table from my previous post.

IQ Range
Classification
70-80
Borderline deficiency
50-69
Moron
20-49
Imbecile
below 20
Idiot

Feeblemind
AD&D, 5th level MU spell but the explanation is on page 62 Players Handbook, under Druid Spell 6th Level, where it says the spell ‘causes the victim’s brain to become like a moronic child.' Sadly no further explanation is given, and I can’t find any other explanation, not even in the DMG spell explanation section (DMG 41-47). So whether the victim can cast spells or not, isn’t clear. I always assumed they couldn’t, why else would the spell be ‘solely for employment against those persons or creatures who use magic spells.’ But using the table above and assuming Gygax had this in mind, it was the 1970s, a Moron is IQ 50-69. Now on PH page 10 looking at the Intelligence table it says that an intelligence of 9 is the ‘Minimum Intelligence for a paladin or magic-user character.’ So, that would imply in typical AD&D confusion (all those words so little clarity) that spell casting or advancing as a magic-user, would be impossible while the spell is in effect.

B/X Cooke Expert X16 describes the 5th level MU spell Feeblemind as making, ‘a magic user or elf unable to think or cast spells becoming a helpless idiot.” Clear on the not casting spells but an idiot is IQ <20. Interestingly Mentzer Expert doesn’t have the spell but it appears in Allston Cyclopedia as a 5th level MU spell, so I assume it reappeared as an extra 5th level spell in Mentzer Companion (my copy is behind a loft hatch, but I think it’s a fair assumption). Allston, page 52 says, Feeblemind, makes the victim, ‘helpless, unable to cast spells or think clearly (as if the victim has an Intelligence score of 2).’ Pretty clear here it's effect as linked directly to an Intelligence score. And definitely supporting the general belief that IQ divided by 10 = Intelligence Score.

From my Argument 1, an Intelligence Score of 3, has to be seen as unplayable, as it's one very minor step up from helplessness.

Reroll, readd, redo - An ability score of 3 is unplayable