Mr. Markwalter

 We are into Unit 3.  Today we start changing things.  I am noticing: ◦ If you copy down the examples as I walk through them, you would have EXACTLY how to answer many of the test questions.  Today: I will lay out my work so that you can copy EXACTLY what I do in your notes.  I will also start checking notebooks along with homework.  If you are missing it, it means you came to class unprepared. That leads to lunch detention.

 In college, you will be expected to take notes on everything  Professors won’t be help with everything.  People get to college and get their butts kicked because they don’t know how to work in class.  One of the greatest keys to success in college is study habits. ◦ Note taking ◦ Studying ◦ Practice ◦ Review

 What do we notice from this chart?

 These are scatter plots  They compare two quantitative variables  We have a response variable which measures an outcome  We have an explanatory variable which may help explain the response variable

 Response variable is usually on the y-axis  Explanatory variable on the x-axis

 If we collect data on people from hospital records and are interested in their life expectancy based on how many cigarettes they smoked per week, our graph might look like this.  Copy it down in your notes with my labels.  Explanatory variable: cigarettes smoked per week  Response variable: life expectancy

 This should go in your notes. 1. Decide which variable should go on which axis 2. Label and scale your axes 3. Plot individual data values

IndividualHeight (in)Weight (lbs) A60120 B62130 C63138 D65140 E66141 F67140 G67143 H68150 I69155 J70156 K72165

IndividualTime spent exercising per week (minutes) Weight (lbs) A0220 B20205 C30205 D30180 E45190 F60195 G90180 H90160 I J K

 Three ways to discuss them.  Copy these down  Direction: upper left to lower right, etc.  Form: Straight, slightly curved, etc.  Strength: how closely the points follow the form  Outliers: points that don’t fit the pattern.

 Positive association: as one increases, other increases  Negative association: as one decreases, other decreases  But association DOES NOT IMPLY CAUSATION

 As the price of the car increases, insurance increases. POSITIVE ASSOCIATION  As age increases, time spent exercising decreases. NEGATIVE ASSOCIATION

 We have a way of measuring the strength and direction of the relationship between two quantitative variables: correlation.  Correlation is called r.  r is measured between -1 and 1

 If association is positive, r is positive  If association is negative, r is negative  The tighter the points are in a line, the closer r is to -1 or 1

 Spend 10 minutes on the worksheet  Expectation is quiet  You may work together  We will review the answers at the end  What is not completed is homework

 Review for next time because standard deviation will return.  Even though it is review, copy it down.  Find the standard deviation of the following data set.  1, 2, 3, 4, 4, 5, 6, 7  Watch me

 Find the standard deviation of the following data set.  2, 2, 3, 4, 4, 5, 5, 6, 6, 7, 8, 8  You try

 Find the standard deviation of the following data set.  2, 2, 3, 4, 4, 5, 5, 6, 6, 7, 8, 8  You try