The rising use of data and science in beauty marketing has led to an increase in percentages, fractions, and statistics. When it comes to percentages and fractions, it is extremely important to understand what they mean.
Often, important contextual information is left out. This can have the effect of boosting the claims brands make about their products.
Let’s look at something simple to begin with, how fractions can be converted into percentages – and vice versa.
2/4 is 50%
250/500 is also 50%
2 and 250 are numerators, while 4 and 500 are the denominators.
This numerator is how many parts of the whole, and the denominator represents the whole.
This comes into play when we look at claims like 90% of people agreed that For’real Serum increased skin dumplingness. What we’re missing is the context of the denominator.
90% could be 9 out of 10 people, or 900 out of 1000 people.
9 out of 10 people is a small sample and probably subject to some sort of bias. If 900 out of 1000 people agreed though, that would be more convincing.
This issue with lack of denominator context is also pervasive in claims using “bioavailability”, “penetration”, “absorption” and “conversion”. These are often claims of comparison – but they’re usually missing the context of how and what they’re being compared to.
How tall is Ranbir if we’re told “Ranbir is 20% taller”? We don’t have the information to know! But we can figure it out if we’re told “Ranbir is 20% taller than the average American firefighter in 2020”
In a similar vein, what does “20% more hydration” mean? We don’t have the information to know! But we have an anchor if we’re told “20% more hydration compared to before use”.
Let’s look at some beauty relevant examples…
40 times more skin penetration…
An important piece of information that’s missing is how was this determined? Is the way that this was determined applicable to the way that their customer will be using it on their skin? Often this data comes from models of skin (things are designed to mimic some aspect of skin, but are not skin), and in vitro (something that isn’t the living, whole organism) or cells. An ingredient might penetrate 40 times more into an individual dermal skin cell floating inside a plastic dish of nutrients over 2 days…but we are not giant dermal skin cells floating inside a plastic dish of nutrients.
What really matters is how the ingredient penetrates human skin that’s part of a living, functioning, whole human person. As well, it’s more relevant if the ingredient or product is used in a way that mimics how we would use it. If penetration increases after 40 minutes of being in a microwave oven…I would argue that information probably isn’t relevant.
90% skin “bioavailability”…
Claims like these often have the same issue as the previous claims we just looked at — like how a measurement was made. But often they also lack another type of context. What’s being measured?
What these claims insinuate is that 90% of what you’re applying to the skin will be “bioavailable” to the skin. But what’s often missing is the context that the 90% is usually a measure of what is “bioavailable” after skin penetration (or the skin model, cell, or in some cases a piece of gel or paper).
Let’s say you have 100 red balls of various sizes.
You shake them through a sieve.
8 red balls have passed through the sieve.
We have 8 red balls out of the 8 balls that fell through the sieve (8/8, 100%).
Is that 100% “bioavailability”?
We need to remember that we started with 100 red balls.
So out of those 100 red balls we started with, only 8 red balls passed through the sieve (8/100, 8%).
So is the “bioavailability” 8% or 100%?
Well, you’re using (and paying for) the 100 balls, so I would say the 8% is the number that’s more relevant.
Note: I have “bioavailability” in quotes because in terms of skincare it’s not well defined. In pharmacology, bioavailability is the amount of a taken drug that reaches the bloodstream.
“Bioavailability” is often used in the marketing of nutritional supplements, but the pharmacology definition doesn’t really make sense because how a nutrient gets used or absorbed can also depend on a person’s current nutritional and physiological state.
The meaning of “bioavailability” in skincare becomes even harder to pin down. It can sometimes mean the amount of an ingredient that reaches the lower epidermis – but there’s no strict or widely accepted definition nor is there a standard way to measure it.
Often “bioavailability” in skincare is just a marketing term to make a product sound more unique and effective compared to its competitors.