If you just,
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this particular table here, let's say. Well how do I predict these four entries?
Maybe I'll say
just look at this movie, okay?
If this movie has got a lot of high rating, just give it high rating.
Like 5, 5, well maybe this is 5 too. This is 4, 4, 5, another good movie.
And make it 4.5. Okay, this one is 2, 3, 4.
Huh, that's a tough call.
maybe I'll look at this row here. Okay.
I'm trying to predict how would user 5 like the movie 3.
But user 5 seems to give 3, 3 all the time.
Maybe. Should also give 3 here.
What about this entry, the movies 7s, gets 1 and 3 and 4,
that's kind of diverse, and this user, I should give 2 and 4.
So it's really hard to say what this might be.
Okay, it could be 1, 2, 3, 4, 5. I don't know, maybe just give an average.
Whatever is the average of all these entries here.
Let's say the average is 3.5, alright 3.5.
Sounds a little like filling out a table in the Sudoku.
Well, in what we just talked about, we actually touched up on a few intuitions.
One is that certain movies are in general better made
than certain other movies.
And certain users are very strict graders or very loose graders.
We have to take into account those things.
We can also, when there's no other help, just give up
and say, take the average of the whole table as the prediction.
That's a very lazy predictor.
So there's some intuitive understanding just emerging.
But none of this is good enough to get you 8%.
Not even close. Have to think little harder than that.
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