In our previous post about Beauty Skepticism we discussed the scientific method and how it can be used to figure out the most likely explanation for any situation. One of the key elements of the scientific method is experimentation. In this post we’ll discuss what makes a good experiment and how you can use it to help figure out what beauty products are best for you.
Hypothesis & Prediction
Whenever you have a question about a new product or some beauty advice you’ve heard the first thing to do when evaluating is to come up with a hypothesis and prediction. For example, a few stylists have said in the comments of our salon products post that the products you buy in the grocery store are different than those you can get in a salon. This leads to the testable hypothesis…
“Are salon products you get at Target different than those you get in a salon?”
This hypothesis leads to the prediction…
“I will notice a difference in my hair if I use a salon product bought at a salon versus one bought at Target.”
Now, you can create an experiment to test this prediction.
The type of experiment you conduct will depend on the specific question / prediction that you make. For evaluating beauty products there are three basic tests.
1. Half and half – Test a product on one side of your face, hair, hands, etc. and test another product on the other side. These tests are better when you want to learn about a product’s immediate impact. Here is an excellent example of a half-face evaluation of the Clarisonic face wash system.
2. Sequential – Another option is a sequential test where you test one product first and then test the next product after. This works better when you want to test a product’s long-term effect.
3. Triangulation test - In this test you take two samples of one product and one sample of the other and test them (on a blinded basis) to see if you can pick out which one is different.
Let’s go through how we might test our hypothesis about salon products.
Experimental Design: Get a bottle of Paul Mitchel shampoo at a salon and get the same type of bottle at target. Apply half a dose from one bottle to one side of your hair and apply half a dose from the other bottle to the other side. Wash & style hair as normal. Note any differences.
Of course, this experimental design is pretty weak because there are a number of variables you didn’t control. Here are a few refinements that may help give you better results.
1. Blind the samples. Since you might naturally have an opinion about what answer you want to get, your observations could be tainted if you knew which bottle was which. Try to disguise the product so you have no way of knowing which side is which. One way is to write on the bottom of the bottle with a marker whether the product came from the salon or from Target. Another way is to have a friend pour out the samples for you. The key is that you shouldn’t know what product goes on what side of your hair until AFTER the test when you’ve made your judgments.
2. Control the variables & repeat. Variables are just things that can affect the results. This can be anything like heat of the water, dirtiness of hair, personal mood, etc. By doing a half-head test you minimize the effect of many variables, but you haven’t gotten rid of everything. Perhaps even your own hair behaves different on one side of your head versus the other. This is the reason you’ll want to repeat this test a number of times before declaring there is (or is not) a difference.
3. Randomizing. And while you are at it, be sure to “randomize” your repeat experiments. You don’t want to continue to test the same product on the same side of your hair each time. Switch it up at random intervals.
After you’ve run the test, you can look at the results and decide whether your original prediction was correct or incorrect. If you found that you could tell a difference between the Paul Mitchel you bought at the salon and the one you bought at Target, that MIGHT mean you’ve learned something. There could be lots of other explanations you’d have to eliminate before you can say for sure, but at least you have some idea. If you couldn’t see any differences, then you can be fairly certain that there aren’t any differences.
The important thing to remember is that any results you get from a single test are only suggestive of what may be true. Only through multiple tests can you really collect enough data to make definitive statements. Also, the results that you get might not be applicable to other people since they have different hair, skin type, desires, etc.
In the lab, we arbitrarily run 30 trials before we consider any conclusions to be valid.
Beauty Brains bottom line
Almost any question you have about beauty products or beauty advice can be answered by creating an appropriate experiment. Start with a hypothesis, make a prediction, then test that prediction to see if it comes true. This is the only way to know what’s true and what’s beauty BS.