Question

a shampoo advertized in your favorite magazine claims to have a secret ingredient that will make your hair thicker and shinier how could you test the claim?

Answer 1

Test the shampoo on different subjects with different hair types (Ex thick, thin) Keep the variables the same for each subject using constants, independent , and dependent variables to test the claim. See if there is any difference in the girls who used the shampoo with the secret ingredient Vs girls who used a regular shampoo with out that ingredient.