/ tests if you're going to be data scientist at big tech web companythis is something you're going to definitely be involved inbecause people need to run experiments to try different things on website and measure the results of itand that' actually not as straightforward as most people think it is what is an / testwellit' controlled experiment that you usually run on websiteit can be applied to other contexts as wellbut usually we're talking about websiteand we're going to test the performance of some change to that websiteversus the way it was before you basically have control set of people that see the old websiteand test group of people that see the change to the websiteand the idea is to measure the difference in behavior between these two groups and use that data to actually decide whether this change was beneficial or not for examplei own business that has websitewe license software to peopleand right now have nicefriendlyorange button that people click on when they want to buy license as shown on the left in the following figure but what would happen if changed the color of that button to blueas shown on the rightso in this exampleif want to find out whether blue would be better how do knowi meanintuitivelymaybe that might capture people' attention moreor intuitivelymaybe people are more used to seeing orange buy buttons and are more likely to click on thati could spin that either wayrightsomy own internal biases or preconceptions don' really matter what matters is how people react to this change on my actual websiteand that' what an / test does