00:01
So we have the sales and the income for this situation, and we're told to let the independent variable be the income and the sales be y, and that would be a common mistake for people to make because they list the sales first that people will think that that's the independent variable.
00:18
But we have our means for the two variables, and then we can find the sum of squared for each of these, and then the sum of squares for the x, x.
00:30
Y and i have those listed in my columns just have to add them up and so we'll go to second in list and sum of the first one ends up being the 1 ,146 .4 for the second one we have the sum of the sum of 696 and for that last sum of squares we have the sum of have a sum of 782 now we're asked to find the regression equation for this line and so i'm going to on part b i just use my lin reg of a plus b x on list one and list two and so stat calculate and that happens to be number eight in my value and we end up getting that the predicted y value, which again is our sales, and that sales is in thousands of dollars, and we have the income is also in thousands of dollars.
01:51
We have a negative 2 .198 plus 0 .6821 .x.
02:00
X and then it says briefly explain the values calculated in part b this tells us that if the if the income is zero then we would expect the sales to be negative 2 .198 in thousands or negative 2 ,198 which again doesn't make sense for our slow as the income rises by one in thousands we expect the sales to go up and that would end up up being 682 .1 because it's 0 .6821 in thousands.
03:00
Next we're asked to calculate in part d we want to look at what r and r squared would be and we know we can find our r value by taking our sum of squares of x y divided by the square root of the sum of squares of xx x times the sum of squares of the y however i'm going to just use my software to find that and that is 0 .875 the r squared value i'm going to list as a is 76 .64%.
03:38
And this tells us that there is a strong, relatively strong, positive association between our two variables.
03:52
And this tells us that around 77 % of the variation in our sales is explained.
04:03
Is explained by this model.
04:12
And then you want for part e, you want the standard deviation for the air, and that value comes out to be, if we do a lin -regg t test, that will give it to us...