1. The zigzag effect
So far, you have seen evidence of a swirling current in 2013 based on medal counts and on performance in 50 meter races. Now, we will look at how a putative current would effect splits in longer races.
2. The current and longer swims
The longest race in the World Championships is the 1500 meter freestyle. The swimmers swim the length of the pool 15 times in each direction. If there is a swirling current, we would expect swimmers in lanes one through three to have fast even splits, when swimming with the current, and slow odd splits, when swimming against it.
3. 1500 m splits and the zigzag effect
Here, we have a plot of the mean split times for swimmers in the final of the women's 1500 meter freestyle. Looking at the dark blue line, we do in fact see fast even splits and slow odd splits for swimmers in low-numbered lanes. This zigzag effect is also present for high-numbered lanes, but it is exactly out of phase, with fast odd splits and slow even splits.
This effect is not present in 2015, shown in the corresponding faded colors.
In the next set of exercises, you will explore this zigzag effect in depth using all of the 1500 meter splits from the 2013 and 2015 competitions.
4. Let's practice!
You have the tools you need to dust the data for fingerprints of a current.