What makes a fair test? Validity, reliability, and replicability in cookies.

Tomorrow is the big cookie showdown at work. Tonight I finally sat down to imagine how to gather people’s feedback about the cookies. I reviewed a bunch of rubrics and score cards, and created a Google Form, drawing from some examples online. When I shared it with the office folks, I received some interestingly heated responses (about cookies!). People want to decide for themselves how to define good texture, chip ratio, and taste.

Of course, personal preference is a huge part of what we eat, and so that makes complete sense. Before this cookie journey, I had a pretty set way of making cookies that *I* liked. Who cares what everyone else thinks? I halve the butter and cream the butter and sugar and eggs so the cookies are cakey. I like my cookies a certain way. It’s who I am.

In preparing for the contest, I started to try out different recipes and ideas about cookies. I even engaged a class of my students in getting feedback. Through this experience, I realized that my preferences may have been unique, and set about satisfying a broader range of tastes. This is much like my experience was in online dating. In trying to make a profile so neutral that it was appealing to all, it doesn’t end up representing who I am very well.

At times the process of controlling for variables and eliminating variation makes an investigation so sanitized that it nonlonger represents reality very well. The disconnect between cognitive science and education application is an example of how decontextualization can create an unfortunate gulf between what are very related domains.

Furthermore, what makes a fair test? I often talk about this with my son as we are trying ideas out in the kitchen. How will we systematically evaluate the results? What are useful variables (changing the design, or recipe) and what are variables that should not matter (like which oven one uses)? Ideally the spectrophotometer in my lab should work the same  as a lab in Guam or chile or tunisia. If the tools are not comparable then the community can’t build on each other’s findings.

Defining criteria for success and validating those measures is important – especially within a community of individuals who may have to compare one batch of cookies (or study) against another one. Is objectivity possible? I often wonder that, as scientists first have to define what they are looking for, and then build the tools to find it. Tests that are not accepted by the community in similar ways are not valid – everyone has a different idea of what makes a good cookie, and those ideas could work in different directions. Those ideas can’t necessarily be summed together without construct stabilization. However, I am not going to go about stabilizing these constructs for this particular contest.

This experience has also allowed me to consider issues of reliability (and replicability) in science. I thought I had a good recipe, I tried it out, it worked well. I made the dough ahead of time. I kept it chilled. However, I am staying with my sister tonight and her oven is different. Both are ovens, both were at the same temperature. We both live at 1 atmosphere of pressure (sea level). Yet, the two sets of results were very different. I took a picture from last week and again from tonight below.

If I had my kitchen, my ingredients, and perhaps was not so tired, I’d go back to my original recipe and make *my* cookies. The ones I like to eat.

I’m not able to do that tonight. I guess I could forfeit, but in reality I’m ok either way. I don’t actually care if I win a contest. The point was the fun of it, and a little community building and competition is OK among friends. After all, I learned a bit. I tried some new stuff. And I had an opportunity to wonder. I like to wonder…..

Below: same recipe, same temperature, same atmospheric pressure, same time, different oven, different cookie sheets….oh well. 

***Photo temporarily removed so as not to identify cookies among possible judges!!!!***


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