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The "Lighthouse Solution" Lesson is part of the full, Web Performance Fundamentals course featured in this preview video. Here's what you'd learn in this lesson:

Todd demonstrates the solution to the Lighthouse exercise.


Transcript from the "Lighthouse Solution" Lesson

>> We're going to take a look at some of that data and compare it with what our subjective opinions were and see how those things measured. So when I did this exercise, these were the scores that I got. Now your scores are likely different than these, I would not expect us all to have the exact same.

And the reason that we would not have the exact same is that these are called lab metrics. As in we got these metrics from running in our own private laboratory. Which is our own machine. Your score is reflected what your instance of Chrome running on your screen size for your computer currently experienced it.

And so it's going to change slightly based on what kind of computer you're using, how big your screen was, where in the world you are, how well the site was serving you content at the time, etc. But when I did this, these are the scores that I got.

And I've color coded them here on the left, which they should have popped in as you enter the numbers, roughly how Chrome would have treated those numbers, whether they were good or bad. And on the right, I calculated the ranking of each and compared it. So the perceived speed rank was whatever you ranked the sites from your subjective which site is fastest, our first exercise that we did.

And then how well they ranked for each of these three important metrics. We didn't include first input delay because likely you're not inputting anything into these sites. So how well did they correlate? For me my metrics seemed to correlate pretty well with my subjective opinion. I thought NPR was the fastest, I felt it was the fastest.

And it had the fastest LCP, the best caminos of layout score, and the second fastest first contentful paint. Overall, the metrics say, this is a good site. It was fast. The second fastest site for me was the New York Times. That's what I felt it was. And the metrics agree with it across the board.

It was the second rank in everything. It was the second fastest FCP, the second fastest LCP, the second best CLS, etc. So this was, at least in this instance, a pretty good representation of my subjective opinion.

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