00:01
Okay, with this question, we are looking at a study that looked into the effects of smoking versus birth weight of infants.
00:18
And what they did in the study is they gave moms a questionnaire, asked them about whether or not they smoked, whether or not the father smoked, and then compared it to birth weight.
00:33
And what they did is all of the moms, they separated the questionnaires for the smoking moms and non -smoking moms.
00:43
And they focused on the questionnaires from the non -smoking mothers.
00:49
And with the questionnaires for the non -smoking mothers, they then separated them into whether they said the fathers smoked or didn't smoke.
00:59
So when we're looking at the data, well, let's just start answering the questions.
01:06
A, ask us, was this an observational study or an experiment? and this was an observational study.
01:24
And that's because there were no treatments imposed.
01:38
They didn't tell the fathers whether to smoke or not.
01:58
They just were taking note of whether they did.
02:02
Did.
02:03
So observational study.
02:06
The explanatory variable is the variable we might think explains what happens with the response variable.
02:20
And they ask us to identify each of those.
02:23
So the explanatory variable here was whether or not the father smoked.
02:39
And the response variable was the birth weight of the infants.
02:51
And they ask us for part c if we can think of any lurking variables.
02:59
Now, a lurking variable is something that can be associated with the explanatory variable and the response variable.
03:07
So the one thing that comes to mind after i thought about it for a second was the overall health slash lifestyle of that.
03:24
The family? and that would be because if the father smoked, then the family overall might not have as healthy of a lifestyle.
03:37
Like maybe they're not as likely as a family unit to be exercising or to be eating healthy.
03:44
And that could also impact the birth weight of the infants.
03:48
And there are other factors too.
03:51
Race, income, the health factor is what came to my mind first.
04:01
And then in part d, it tells us that they adjusted the results and they asked us what that means.
04:10
And they just used statistics to adjust the final results to accomplish.
04:26
To account.
04:27
Count for and hopefully eliminate bias.
04:38
So there were some things they were aware of and they made some adjustments to make the results basically more accurate.
04:47
All right.
04:48
Part e ask us for summary statistics for both groups.
04:58
And what they ask us for, so let's go ahead and start a little chart for the non -smoking group and the smoking group.
05:08
We're asked to come up with the mean, with the median, with the standard deviation, q1, and q3.
05:20
And, you know, they give us the data.
05:23
What i did is i used my ti -84 calculator.
05:28
And, you know, there's instructions in the book how to use different types of technology, but this is what i had handy.
05:35
I put in the stat list, so stat edit.
05:41
I put the data for the non -smoking fathers, the kids birth weight in list one, and then for the kids with the smoking fathers, their birth weights in list two.
05:53
And then in order to get summary statistics, once you have all that data, and i can just show you, i put it all in, it keeps going, you can calculate your summary statistics.
06:08
So i go back to stat, and this time i'm going to go to the drop -down menu for calculate, and i'm going to calculate one variable stats, which is number one.
06:20
And i'm going to start with the first list.
06:22
This would be the summary statistics for the kids with the non -smoking fathers, and we just go down to calculate and hit.
06:34
Enter and i can see the mean is the x bar is this first value the 3665 .5 s of x is my standard deviation then i have minimum q1 median q3 max and then i can do the same thing i'm just going back to calculate back to one variable stats but this time i just need to change the list i want to do the same thing for the smoke and that gives me those same statistics for the smokers.
07:12
So let's write those down.
07:17
So for the non -smokers, the mean was 33665 .5, and this is grounds...