2021 Season pit stops: Rounds 1 to 6

The pit stops of the season

The Championship battle seems to be shaping up to be a close one this year. With such small margins, the pit crews may end up being crucial in the World Championship decider. Let’s take a look at the pit stop crew and their performance in first 6 races of the year

Methodology

The pit stop data was obtained from DHL’s Fastest Pit Stop Award website.  This data was then compiled and processed in a few distinct ways.

For the full data analysis, the data was used without filtering any data points. The information was grouped by either driver or team and then the average time and other descriptive statistics were calculated from ALL the points.

As for the filtered data analysis, the data was grouped by either driver or team and filtered using the Generalized Extreme Studentized Deviate test (GESD). This test progressively evaluates anomalies, removing the worst offenders and recalculating the test statistic and critical value. It has shown better performance than IQR filtering methods in some previous scenarios so I decided to use it for this analysis. One important note about this method is that I limited the number of anomalies to a maximum of 20% of the data. This way if a pit crew has been making many mistakes, some of them will remain on the data and the team/driver will be penalized for them. 

Finally, for the pooled data analysis, the data was grouped by either driver or team and then filtered using the GESD method.

After the data was processed, I created some nice charts for you to see. I hope you enjoy them.

Interpretation

For the non-filtered data, you will see that outliers—abnormally low or high values— will drag the mean (average) time drastically towards the left or right of the plot. This average time will be arithmetically sound, but perhaps not representative of the average pit stop time you will see from a particular pit crew. It is because of this that the filtered data was used, to create a more representative average pit stop.

The charts have three distinct intervals which represent the density of the data. First, the 50% interval contains 50% of the data and it means that you would expect most pit stops to be around that time. Second, the 80% interval is wider and contains perhaps some pit stops that were abnormally fast or slow. Finally, the 95% interval contains most of the data, including perhaps abnormally fast or slow stops. If a data point is not included in any of these intervals, it can be considered as a bit of an outlier.

As you will see, these intervals are asymmetrical for some drivers/teams. These intervals tend to be shorter on the left side, and longer on the right side. This is because it’s easier to make a mistake and get a slow pit stop, than being perfect and getting a quick pit stop.

One final note. A couple of years ago I used the geometric mean for my analysis instead of the arithmetic mean. This year I decided to go with the arithmetic mean since it’s a lot easier to interpret. While it has the downside of being massively influenced by outliers, it shouldn’t affect the filtered analyses since the outliers were already removed.

Team pit stop times

To see the hi-res png images click here and here.

Full data

Let’s start with the teams, shall we? First, we will take a quick look at the full data chart, and then proceed to properly analyze the filtered data plot.

If we do not filter the data at all, we see that the fastest pit crew so far has been the one of Ferrari. Their average time of 2.63 seconds is the fastest by a margin of over 1 tenth of a second over the second-placed crew. The slowest crew is the one of Alfa Romeo, with an average time of 5.12 seconds, which may seem incredibly slow.

Having said that, these numbers are not very representative of their performance. Just take a look at the average time of Alfa Romeo (the diamond-shaped point). It is placed to the right of most of the points! As I’ve said, this average is massively influenced by outliers, and Alfa Romeo has two big outliers. Just think about it. A pit stop of 35 seconds equals 10 stops of 3.5 seconds. That will heavily affect our numbers, so perhaps we shouldn’t take much from this first chart.

Filtered data

The filtered data chart makes more sense. Red Bull’s crew is now ranked as the fastest with an average time of 2.34 seconds. Alfa Romeo went from being the slowest crew to the third fastest. If you take a look at the points, it makes sense. They have been consistently fast and their average time was just very skewed due to the 35-second pit stop. 

Take a look at Ferrari’s average time. Did you notice that it didn’t change at all? That’s because the anomaly detection algorithm didn’t detect any anomalies in their data. While they haven’t been the fastest, they also haven’t made any serious errors this season. A faster average time is great, but not if every 10 stops the crew makes a bad mistake.

As you can see, the pit crews from Red Bull to Mercedes are very evenly matched. The delta between Red Bull’s time of 2.34 seconds down to Mercedes’ time of 2.66 seconds is of just 0.32 seconds, which is quite impressive. Still, during a race those 3 tenths of a second could be the difference between losing, gaining or keeping a position on the track.

The worst performing crew has been the one of Haas. Their filtered average time of 3.59 seconds is the slowest by far, with them being almost 7 tenths away from the second slowest team, McLaren.

Driver pit stop times

To see the hi-res png images click here and here.

Full data

Just as with the team’s data, the full chart shows a funky picture of the pit stop times if we do not remove the outliers. You can see drivers like Antonio Giovinazzi and Mick Schumacher with stop times of over 5 seconds. Were their pit crews that slow? Again, it may not be the best idea to draw many conclusions from this chart. 

Filtered data

The filtered data shows a clearer picture of the situation. From the 20 pit crews that have participated in the current 2021 Formula 1 season, 14 have an average time of fewer than 3 seconds.

Max Verstappen’s crew has had the best pit stop times up until now, with an average time of an incredible 2.19 seconds per stop. The only pit crew that comes even close to that time is the one of Kimi Raikkonen. Their average time of 2.28 seconds per stop is less than one-tenth away from the fastest which is quite impressive.

There are a couple of results that I found particularly interesting. First, the average stop time of Pierre Gasly’s crew, and second, the pit stop times of Sergio Perez’s crew.

Regarding the Gasly situation, there is a very obvious slow stop of close to 7 seconds that is skewing his data. Why wasn’t this outlier removed? As I’ve stated in the methodology section, I limited the number of anomalies to just 20% of the data. If you take a look at Gasly’s full data, he has 3 very slow stops— one of around 7 seconds, one close to 9 seconds and one of over 20 seconds. The algorithm removed the two slowest ones but decided to keep one of close to 7 seconds to comply with the directive of a maximum of 20% of points detected as outliers. I think this is fair since this way his average time is penalized due to so many slow stops. In the next few races, this slow time may be detected as an outlier as long as his pit crew stops making more mistakes.

With Sergio, the situation I thought was interesting for different reasons. His crew hasn’t been slow, but they haven’t been as fast as you would expect from Red Bull. If we remove the slowest pit stop of the chart—the one done in the latest 2021 Azerbaijan GP—his average time would just improve to 2.50 seconds. While that time would put his crew among the top 5, it’s still 3 tenths slower than his teammate’s time.

Pooled pit stop times

To get a hi-res png image click here.

The filtered pooled pit stop data is just meant to visualize the pit stops done in this season as a whole. In this chart, the top stacked histogram shows how the times were distributed with an interval of 0.1 seconds. For example, all 100% of the pit stops done between 1.9 and 2 seconds were done by Red Bull. For times between 2 and 2.1 seconds, 50% of them were done by Red Bull and 50% by Aston Martin. 

The average times shown at the filtered team data are also shown in this plot. You can see how Red Bull leads this way, but most teams have respectable averages. The only pit crew that really stands out is Haas’ with the previously mentioned time of 3.59 seconds per stop. 

Final remarks

First of all, I hope you have enjoyed this analysis. I am intending to make this another one of my weekly/biweekly series. I think that this is a type of analysis that can easily be updated every week to keep you up with the performance of the pit crews.

As usual, Red Bull has been dominating in this field, particularly with fantastic performances coming from Max’s side of the garage. I would also like to put special emphasis on Alfa Romeo’s crew. They have been flying under the radar up until now but their performance has been stellar.

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