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Multi-variate Regression Quiz - Intro to Machine Learning

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    So this is actually a surprisingly challenging question if you've never done
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    this before.
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    So let me dissect it for you first.
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    I'm going to only look at the very first feed over here and
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    ask how much does Y grow as you vary X.
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    And you can see as we add 20 to X, from 20 to 40, or another 20 to X.
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    Every time, x1 goes by 20, y goes by 100.
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    So the factor that goes in over here is y divided by x.
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    It is a five.
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    I hope you got that right.
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    As we do the same thing for the x2 variable, we find when x2 goes by 20.
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    Y only goes up by 50.
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    So we divide 50 by 20 and divide, at 2.5.
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    Now if we left it at this and believe this is the formula and
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    this number of here doesn't exist then what we will predict for
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    this value over here is 20 times 5 plus 80 times 2.5 and that is 300.
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    So we get 200 too large.
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    So we have to subtract minus 200.
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    And it turns out, the way I made this table,
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    this is actually the correct equation.
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    So you can check any value in this table over here and you'll find that
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    this specific linear equation exactly explains the value over here.
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    Now that's an artifact.
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    In reality we don't have such nice situation, where a,
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    what we call a linear hyperplane explains data so well.
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    But it gives you a sense that the predictor variable, in this case,
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    net worth, could be a factor of more than one input variable and
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    that is called multi-variate regression.
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    And all you have to know about this,
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    there's a piece of software that just does it for you.
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    So you can actually plug data like this into a table and
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    out comes the correct result.
Title:
Multi-variate Regression Quiz - Intro to Machine Learning
Description:

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Video Language:
English
Team:
Udacity
Project:
ud120 - Intro to Machine Learning
Duration:
01:46

English subtitles

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