# How important is the Design event in Formula SAE?

In this post I’m going to discuss the importance of the design event in Formula SAE competitions.  It will start with a brief explanation of the design event, and tips on how to do well on the event. Using the results from the past competitions answer the question:

How important is the design event in Formula SAE?

The design event is part of the static events at Formula SAE competitions.  Its purpose is to judge the students engineering effort into the design of the vehicle.  As stated by the rules:

“The car that illustrates the best use of engineering to meet the design goals and the best understanding of the design by the team members will win the design event.”

Each team has approximately 30 minutes for their presentation and they are divided into:

• Set up – 3 minutes: for placing your car (in finished condition), students and any other materials for presentation in the judging area.
• Introduction – 1 to 4 minutes: where the team can present the car, their goals, and mention whatever they want to emphasis about the car.
• Judges Q&A 25 to 28 minutes: Here the judges will ask the students the fundamentals about the car, its design, governing physics, and validation.
• After the Q & A the team has to let clear the area quickly for the next one in line.

Tips on how to prepare for the design event:

• Design report and Design spec sheet: the judges will read this information before the design event.  Consider the design report as the resume of your car, it should emphasize the strong design parts of the vehicle.
• One student per judge: a minimum of one student at all times per judge; the judges want to see that the team has an understanding of the vehicle and score less teams where one student answers all the questions.  I would recommend at least 2 students per judge.
• Presentation material availability: have your data, analysis and everything else that you might want to show the judges near and available.  Here is where posters, binders and parts prototypes help to explain your car to the judges.
• Questions the judges want you to answer: students.sae.org has a document with these questions (find it here).
• End of Design Q&A: leave pictures of your car with the judges, it is allowed by rule C5.14 and helps the judges remember your car.

Now lets move to the question: How important is the design event for the overall Formula SAE competition?

I started by collecting results from Formula SAE competitions in the USA (a total of 12 competitions between 2006 and 2013).  From the results collected, design, endurance, and overall scores where extracted.

First the data of one competition is explored using a scatter plot of the endurance vs design score.

The plot above shows visually signs of a linear relationship between the scores.  To investigate further the mean of the endurance scores is plotted vs the design scores below.

Here a linear relationship between design and endurance score is more visible.  In order to confirm formally this linear relationship the Pearson correlation coefficient was calculated between each of these scores.  This coefficient measures the linear relationship between two variables.  And here the variables used were design and endurance scores and then design and overall scores.

To summarize, all correlation coefficients were significant (p < 0.05) with most of them attaining higher significance (p<0.01).  The mean of the correlation between  design and endurance score is 0.484 and the mean between design and overall score is 0.730.  Unfortunately, there is no established threshold value for the Pearson correlation coefficient to establish a linear relationship between two variables, here due to the nature of all the uncertainty and complexity of the competition a perfect correlation was not expected.  However, there are a number of conclusions that can be extracted from the data.  First, since the correlations are positive this means that the design event score is proportional to the endurance and overall score.

Knowing the possibility of a linear relationship between design and endurance, and design and overall score, linear regression is used to find the contribution of the design score to these events.  The linear regression used the design score as the independent variable and endurance or total score as the dependent variable (see equations below).

$Endurance_{score} = \beta_0 + \beta_1 Design_{score}$

$Overal_{score} = \beta_0 + \beta_1 Design_{score}$

The Beta coefficients are summarize in the following table, with the significant of Beta 1.

The Beta 1 coefficient quantifies how much the endurance and overall score is increased by increasing the design score by 1 point.  For the endurance score between all the competitions reported here for an increase of 1 point in design a mean of 1.695 points are increased in endurance; in the overall score for each point increase in design, a mean of 5.343 points are increased in the overall score.  A clear picture is established when revising the standardized Beta 1 coefficient, which measures the effect or contribution of the independent variable (design score) to the dependent variable (endurance or overall score).  On average the design event score can predict about 50% of the endurance score and 73% of the overall score.

Throughout the discussion of the correlation results it was assumed that the design event was the causation for the other scores.  This was assumed because a team that was able to prove the design judges that their design is correct and meets the competition goals is the one that will perform better at the dynamic events, like endurance.  In the opposite way, a team doing well at the dynamic events will also be likely to have a good score in the design event, but this is because in order to have good dynamic scores, teams have to do their homework and design correctly the car for the competition objectives.  This post when referring to design is referring to good design that also involves manufacturing and testing!

With this knowledge, teams on all levels should understand that the tenth of a second that they needed or the saving of 10 pounds (4.53 kg) can be better found at the design stage. Give the design competition the importance that it has.  Think of it as if were 750 points out of the 1,000 points of the competition because according to the numbers shown before that statement is not that far from true.

I would like to know your thoughts, opinions or stories about the design event and how it influenced the dynamic events.

PS:  The idea for this post was a product of good conversations at the Formula SAE Michigan 2013 and Baja SAE RIT 2013 competitions.  In the conversations the question of how important is the design event was brought to my attention and I try to answer it here to some extent.

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