Why I prefer the average-median hybrid for slider composites

Left to right: average, median, and average-median hybrid composites, all made from the same set of 11 characters.

In another post I described my interest in making composite characters using DD2's character creator. By taking different characters and combining them, we can

(1) run fun community projects where many people contribute artistically to the same character, and

(2) create a result that's somehow representative of everyone's contributions.

But the "somehow" matters: once we get character creation info, how exactly should we use it?

Before answering this, it would be helpful to pause for a second and distinguish between sliders and selections. With sliders, the numbers represent some relative position along a scale between two extremes (e.g., nose length, upper body muscle mass, rear size). On the other hand, selections (base head, muscle style, eyebrow shape) don't, because they aren't arranged along a continuous scale the way sliders are.

Today I'm going to focus on sliders. The question is: once we get slider data from a bunch of different characters, how should we use it?

Averages vs. Medians for Slider Composites

Below is a set of 11 female human characters. If we look at them, we can see some striking variation, but we also see some patterns. Seven of them (the ones in the first two rows) look relatively normal and generically attractive.

The three faces from earlier all blend slider data from these 11 characters.  Top row: u/Motor-Garden's unnamed female human, u/RemoteSevere's Ani, Scratching Catto's unnamed female human. Middle row: my own Lenore and Gwenyvere, u/JeanPiereLucDujardin's Yla the Valkyrie, u/Puzzled-Cod-1757's Morgana. Bottom row: madg0dspawn's Gori, Jundaei, Seniyqe, and Rhozrym. Linls to public sliders in this caption.

On the other hand, the four on the bottom row are rather unusual.

We want to combine them into a composite character, but how?

First, we need to choose a base head. Since base heads are selections and not sliders, we can't average them. Instead, we choose the most common one: #23, which occurs in four of these 11 characters.

Now we need to figure out what to do about the sliders. Many people suggest using the average (or mean), that is, the figure you get when you add up a set of values and divide it by how many there are. If we plug their facial sliders into a spreadsheet and calculate the average, it returns a set of values for us which, when inputted into the character creator, look like this:

What we get when we average out the sliders of the 11 characters above, using the mode (most frequent value) for the base head.

The benefit of using the average here is that the result looks unique, and that everyone's slider choices are incorporated.

But is it representative of the characters above? Well, maybe. But "representative" can mean different things. It can mean that every character influences the final result, or it can mean that the final result resembles the typical character. The average is good at the first kind of representation, but not always the second, because it in a small sample like this one, it tends to skew the result towards extreme outliers like some of the characters on the bottom row.

(Sidenote: "skewed" doesn't mean "ugly." While probably not what most people go for in the character creator, I actually think this face would be very pretty in real life. But that's just me).

An alternative to using the average is to use the median, that is, the middle value that occurs when you arrange a numerical set in order.

When we plug these slider values into our spreadsheet and it returns the median, we get a face that's more generically good-looking, but perhaps less distinctive than the one above:

Using the median sliders from the characters above produces a result that looks more generic.

This is because, unlike an average, a median tends to be more resistant to outlying values. For example, consider the nostril size settings of the original eleven characters (median in bold):

-100, -75, -44, -42, -29, -17, 0, 0, 2, 77, 100

In theory, a set with fewer outliers, say

-46 -45, -44, -42, -29, -17, 0, 0, 2, 3, 4

would not affect the appearance of the median character's nose at all, although it would probably change the average character's nose noticeably.

In sum: in a small sample like this one, using either the average or the median has pros and cons. The average gives us something more representative of each character but less representative of the typical character. The median is better at capturing the typical character, but it ignores how extreme the non-middle values are.

The Best of Both Worlds: The Average-Median Hybrid

What if we blended the average and the median for each slider? One simple way to do this is to take the value halfway between them. For example, in our set of 11 characters above, the average height is 191 and the median is 198. The gap isn’t huge, but it’s enough to show that the typical character runs tall. The midpoint between these values is 194.5 (which we can round as needed). This approach still lets the median pull the composite toward taller values, while allowing shorter outliers to temper the effect.

When we apply this formula to the characters' face sliders, the result is a face that's more distinctive than the median but less skewed towards extremes than the average:

What we get when we use the halfway point between the average and median.

There's no perfect or optimal way to represent an entire character set, especially given the limitations imposed by DD2's character creator (like having to choose a base head). But overall, I like the average-median hybrid the best; it produces a look that's more representative of the typical DD2 character, but at the same time, it allows each and every character to influence the result.