00:01
So we have 15 sets of data showing the mean number of cigarettes smoked per day and then the age or the longevity or the age at death.
00:09
And these were of men, 15 men who were over the age of 50.
00:14
And we want to know, first of all, what is the explanatory variable? and the explanatory variable would end up being the mean number of cigarettes per day.
00:28
And the response variable, oh, i'm sorry.
00:32
And the response variable is under the same thing.
00:34
The response variable is the age at death.
00:42
Question two asks, create a scatter plot.
00:45
And i'm going to create a scatter plot.
00:48
However, i'm not going to go through the process of being real accurate in graphing it on my calculator.
00:57
And you basically see some dots here, a couple of dots here.
01:01
You see a dot here and here, here, here, here, here, here, here.
01:07
And there definitely appears to be a negative association.
01:10
So number three asks, does it appear to have a linear relationship? yes, there appears to be linear.
01:17
It's not totally.
01:18
And it appears to have a negative association.
01:23
Now, question four asks to compute the regression and the correlation coefficient.
01:29
So i'm going to utilize my linreg.
01:35
And i have calculate number eight.
01:38
And i have data in those lists.
01:40
And when i do, i find out that the y hat is equal to the 86 .1705, roughly 7, and then minus 0 .67.
01:54
And that's going to round to 7, 0 times x.
01:57
And then it asks you to get the correlation coefficient, which is r.
02:01
And it's a negative 0 .6845.
02:04
Now, interpret the slope and the y -intercept in this context.
02:10
And the slope is the change in y over the change in x.
02:16
And so we see that as x increases, as x increases by one cigarette per day, we have a relationship that the longevity drops by about 0 .68 years.
02:35
So as x increases by one, longevity drops to this.
02:40
Now, what does this say? if you smoke, the y -intercept tells us that if you smoke zero, then they're predicting the age at death to be 86 .2 years...