Carrot Cake Cookies (makes 24 mini-cookies)

I know what you’re thinking: “I love food blogs, but I just wish they talked more about experimental design and statistical analysis.” Lucky for you, dear reader, my AP Stats students and I are here for you with two recipes for carrot cake cookies (one regular and one vegan), and a blinded matched pairs experiment to help you decide which one to try.

Oh, that’s not what everyone was thinking? Whatever, y’all. It’s the end of the school year, and we’re just trying to push through.

Real food?

Yep! No refined grains or sugars for the kiddos. Michelle Obama would be so proud.

Cook time:

About 25 minutes of prep work + 30 minutes to chill the dough

 + 11 minutes to bake

Price: $3.50/batch or about $0.15/mini-cookie.           

Ingredients

Regular                                                                                Vegan

1 cup rolled oats                                                              1 cup rolled oats

¾ cup whole wheat flour                                              ¾ cup whole wheat flour

1 ½ tsp baking powder                                                  1 ½ tsp baking powder

1 ½ tsp ground cinnamon                                             1 ½ tsp ground cinnamon

1/8 tsp salt                                                                         1/8 tsp salt

1 tsp vanilla extract                                                         1 tsp vanilla extract

½ cup maple syrup                                                          ½ cup maple syrup

2 tbsp butter                                                                      2 tbsp coconut oil

1 egg                                                                                     1 mashed banana

1 cup grated carrots                                                        1 cup grated carrots                     

½ cup chopped pecans                                                   ½ cup chopped pecans 

           (optional)                                                                            (optional)

Directions

1. Mix the dry ingredients (oats, flour, baking powder, cinnamon, and salt) together in a mixing bowl.

Avoid the temptation to put in a big heaping scoop of oats, because they can dry out your cookies. I’d be the biggest hypocrite in the world if I told you to measure carefully, but you know… don’t get crazy.

2. Mix the wet ingredients in a smaller bowl or measuring cup.

Regular: Melt the butter, then whisk together with the egg and vanilla. Stir in maple syrup.

Vegan: Use a food processor to mash the banana. Melt the coconut oil, then whisk together with the banana and vanilla. Stir in maple syrup. (If the syrup was in the refrigerator, it will cool the coconut oil, creating little solid blobs. You can pop the mixture in the microwave for a few seconds to get everything melty again.)

3. Put everything together and chill the dough.

Stir together the wet and dry ingredients then fold in the grated carrots. Chill the dough in the refrigerator for about 30 minutes and preheat the oven to 325°.

4. Scoop cookies onto the cookie sheet and bake.

Line your baking sheet with parchment paper, then use a melon-baller or spoon to scoop out 24 round cookies. Bake at 325° for 11 minutes. Take the cookies out of the oven, and leave them on the warm baking sheet for a few more minutes as they cool. 

The Experiment

To allow for strong comparisons and control for lurking variables, both recipes were prepared the same way except for a few key ingredients: in the vegan cookies, butter and egg were replaced with coconut oil and banana. Since I only have one Pampered Chef pan, the cookies were baked in three batches, and each batch included about 8 regular cookies and about 8 vegan cookies to guarantee that recipe preference wouldn’t be confounded with variables like cook time, oven temperature, or freshness.

To test recipe preference, my students decided on a matched pairs design (where each person tries both recipes but in a random order) to control for person-to-person variability. They also decided the design should be blinded – not only did they not know which recipe was which, but they didn’t know that one of the recipes was vegan (although they checked a complete list of ingredients for allergens before consenting to participate in the study!).  After tasting each recipe, they rated the recipes on a scale of 1 to 10.

We analyzed the data two different ways: we looked at the difference in mean ratings for the two recipes and we looked at the proportion of the sample who preferred regular cookies. Each dot in the plot below represents a student’s rating of recipe 1 (regular) minus that student’s rating of recipe 2 (vegan). So a value of 1 means the student rated the regular recipe one point higher than the vegan recipe. Two data points were excluded, because of #realdataproblems. Looking back, I shouldn’t have called them recipe 1 and recipe 2, which are easily confused with 1^st recipe tried and 2^nd recipe tried. 

At first glance, it seems like these results prove students prefer the regular recipe. On average, students rated the regular recipe 0.24 points higher than the vegan recipe, with 12 of the 21 students (57%) rating the regular recipe higher than the vegan recipe. However, these results aren’t statistically significant, which means the results could have occurred just by chance. For simplicity, let’s just think about the proportion who prefer the regular recipe. Imagine that students had no true preference and their choice of which one to “prefer” was as random as a coin flip. Even flipping coins, we’d expect to get a "preference" this extreme (57% or higher or 43% or lower) about 51% of the time (a p-value of 0.51). So this experiment doesn’t provide convincing evidence of true preference for one recipe over the other.

As an anecdotal side note, I made the vegan recipe again last night, and they were appreciated by herbivores and carnivores alike.

Print regular recipe

Print vegan recipe