Wednesday HW!

Tonight's HW = Exploring Residual Plots!

Please complete the "Intro to Residual Plots" worksheet provided in class!

• Intro to Residual Plots
• This assignment will help us to explore how to create residual plots and what they tell us!
• What is a residual plot?
• A graph that shows the residuals on our y axis and the x values (or sometimes predicted y values) on our x axis!
• Question 1/2 (there really isn't a question 1, just use the info in 1 to do 2):
• Use the equation given and/or the graph shown to find the residual for each point
• Then, create a residual plot below using these answers to #1:
• Label your x axis of the residual plot with the same x-values from the scatter plot
• Plot points to represent each residual
• Coordinates = (xcoordinate, residual for that point)
• Question 3:
• 3a, 3b--you got this
• 3c--think about what part of the residual plot represents the LSRL and what the residual plot is showing us about the line/points
• The only bad answer here is a blank paper! Think!
• Question 4:
• Now, try to sketch a residual plot without using any numbers based on the scatter plot show...
• Consider your answer to 3c
• Consider how your residual plot in #2 compares to the graph in #1
• Consider what you know about positive and negative residuals--think about how many points should be positive residuals and how many should be negative, as well as if any points should have a residual of 0!

Two's Day HW

Tonight's homework is fairly short--so make sure you put in a legit, AP-exam level effort!

1.) Interpret slope and yintercept" half sheet (or look below, or linked below) 

• The linear regression equation for the relationship between the "number of hours of sleep the previous night" and "time to complete a task (in minutes)" is below. Use the equation to interpret the slope and y-intercept. 
• predicted completion time = 12 - 0.36(hrs. sleep previous night)

2.) Please complete the 3 SAT MC (linked below if you need it). SHOW ALL WORK for questions 5 and 7 to earn homework credit!

• If you use 1Var Stat for #5 just write "1 Var Stat" and "Median = ___" as your work
• Or, if you just use the graph, mark up the graph as your work for #5
• For #7 just show the subtraction

Here's a link to the homework questions if you lost yours or were out:

• 3 SAT MC and Interpret Slope, YInt HW

Tomorrow's stamp will be to score your interpretations and AP MC using a provided scoring rubric/key. Then we'll start to get more into residuals and what "best fit" actually means--see you there!

Also, if you're curious, here's our tentative plan for the rest of the unit:

• Weds (10/23): What does best fit mean? + Residuals and residual plots (ch. 8)
• Thurs (10/24): What does best fit mean? + Residuals and residual plots (ch. 8)
• Fri (10/25): What does the coefficient of determination (R^2) tell us? (ch. 8) + How can we read a linear regression computer output? (ch. 8)
• Mon (10/28): AP FR Group Work (ch. 7/8)
• Tues (10/29): How can we write the equation of the LSRL algebraically? (ch. 8) + AP MC
• Weds (10/30: Ch. 8 Vocab Quiz, Ch. 8 Wrap Up
• Thurs (10/31): Ch. 8 Interpret Quiz + Ch. 9 Intro (Outliers, Leverage, Influential Points)
• Fri (11/1): Outliers, Leverage, Influential Points (ch. 9)
• Mon (11/4): Outliers, Leverage, Influential Points Wrap Up (ch. 9), What does re-expressing data mean? (ch. 10)
• Tues (11/5): Re-expressing data (ch. 10)
• Weds (11/6): Unit 2 Vocabulary Exam (25 min) + Review
• Thurs (11/7): Unit 2 AP FR and AP MC Exam
• Fri (11/8): Probability Intro Classwork! (new unit; ch. 14) 
• *Note: I will be out on this day; you will have a graded classwork with the sub

After this unit we'll be a little ahead of last year's pace, which is fantastic! Last year we started probability on November 16th; this pace will have us starting probability on November 12th. 

Monday = STUDY!

Be sure to STUDY tonight--let's all start off our second unit strong and earn an A on tomorrow's quiz

Tuesday's Quiz:

• Vocab Section (all multiple choice):
• Scatterplot
• Explanatory (Variable)
• Response (Variable)
• Lurking Variable
• Correlation
• Remember, correlation only measures the strength and direction of a linear association
• Know how to determine if a correlation is strong/weak based on the r value
• Be able to compare r values and determine how two correlations are similar/different--determine which of two correlations is stronger/weaker
• Also be sure to know the "facts about correlation" (r doesn't change if we switch axes, doesn't change if we convert all data to z scores, doesn't change if we change units of x or y, and r doesn't have units)
• Positive Association 
• Negative Association
• Y-Hat
• Open Ended Section:
• Describe an association (like the precip v. cucumber yield or ankle range v. balance score, or # missed classes v. exam score examples)
• Other possible questions:
• Identify mistakes in a correlation statement (like Friday's stamp)
• Identify a potential lurking variable (like Friday's stamp)
• Create scatterplot, find r, R^2, equation of line of best fit on graphing calc
• Review:
• Calculate a probability/% based on a Normal model (normalcdf)--focus is on showing work
• OR, find cutoffs given a % with a Normal model (invnorm)

After our quiz we'll get back to work with residuals--see you there!

Weekend HW!

Weekend HW (lots of writing/interpreting):

1.) Describe the association between "number of missed classes" and "exam score." -- this is on the paper we had with our "notes examples" about cucumbers and ankle range of motion. Or, here's the context:

2.) Textbook Page 189 - 193 : 11a, 13abc, for 13's context also interpret the yintercept, 35cef

• For 13c this is called a "residual"-- for this homework just worry about the math
• For 35cef you'll need to find the equation using your graphing calculator (x = fat, y = calories)
• Period H: Here's some help with interpreting the y-intercepts since we didn't get to it in class:
• Remember, the y intercept occurs whenever the x = 0
• We just want to take this idea that "x = 0" and turn it into the given context
• For example--back to ankle range of motion and balance scores...
• The yint = -1.993, so "when x = 0, y = -1.993." 
• In context, "when ankle range of motion (x) = 0, balance score (y) = -1.993"
• Sometimes the y-intercept has an unrealistic interpretation--if so, we have to comment on that; in this case, the y-intercept is unrealistic because a balance score cannot be negative!
• Read the full interpretation in the image below...

3.) ALWAYS CHECK YOUR ANSWERS!

• Here's the answer to the "describe the association" question:
• "Based on the scatterplot the association between number of missed classes and exam score is roughly linear, negative, and pretty strong with a correlation of -0.79; generally, as the number of missed classes increases, exam score decreases."
• Check the back of the book for the textbook stuff....
• However, any interpretations of slope/yint MUST start with "THE MODEL PREDICTS," which is not done in the back of the book.
• Here's the answer to "interpret y intercept" (question I added) for the context in 13:
• "The model predicts that if a house has a size of 0 square feet its predicted price is about 47.82 thousand dollars. This is unrealistic because a house would not exist if it were 0 square feet."

We will have a chapter 7 quiz to start class on Tuesday!

• Open Ended Section:
• Describe an association
• Maybe an open ended like today's stamp (identify mistakes with statements about r, hypothesize about a lurking variable)
• Vocab Section:
• Scatterplot
• Explanatory (Variable)
• Response (Variable)
• Lurking Variable
• Describe an association (what do we describe?)
• Correlation
• Also be sure to know the "facts about correlation"
• Positive Association 
• Negative Association
• Y-Hat

If you were out today we discussed how to interpret slope and y-intercept--there are some notes to get before this, but here are the end products for our interpretations:

Thursday HW

Thursdays HW = Stumps/Larvae Worksheet

• Please complete the "Unit 2: Bivariate Data!" worksheet provided in class or linked below. AND ALWAYS CHECK YOUR ANSWERS! (Also linked below)
• You must write a complete sentence and fully attempt the last two questions to receive hw credit--use your resources!
• Thursday’s homework!
• Questions a, d, and e are all based on using your graphing calculator!
• The instructions in your textbook are based on an older calculator (TI83), so if you have a newer (TI84) or a Casio calculator you'll have to google this and (maybe) watch a video
• Google: "how to create scatter plot on a _____"
• Google: "how to find correlation on a _____"
• Google: "how to find the linear regression equation on a ______"
• Or, watch AP Stat Guy Unit 2 Videos #1 and 2!
• The answer to question (C) on the key is not great...here's a better version:
• c.) The association between the number of stumps and the number of beetle larvae is positive, roughly linear, and moderately strong with r = 0.916; as the number of stumps increases, the number of beetle larvae increases.
• Need help with interpreting slope?
• Check out this AP Stat Guy Video about interpreting slope/y int!
• AP Stat Guy: Interpret Slope and YInt
• You must interpret slope/yint in a complete sentence to earn full credit!
• Homework answer key:
• Tuesday HW ANSWER KEY
• ALWAYS CHECK YOUR HOMEWORK ANSWERS! (CLICK THE LINK ABOVE!)

Tomorrow we'll wrap up any/all correlation notes and start to talk about interpreting slope and y-intercept. See you there!

Weds HW (Due Thurs)

If you were absent last week for either our vocab (Weds) or math test (Thurs) you must make up your test(s) this week! You can do so after school Thursday or during any study hall/lunch any of those days. 

• *I am not after school Tues or Fri, so if you have to do the test after school it must be Weds or Thursday

Wednesday's HW = Stumps/Larvae Worksheet -- DUE FRIDAY

• Please complete the "Unit 2: Bivariate Data!" worksheet provided in class or linked below. AND ALWAYS CHECK YOUR ANSWERS! (Also linked below)
• This HW was originally due tomorrow, but it won't impact our work in class tomorrow, so I'm going to extend the due date to Friday. However, you might get a lil more (short/10 min)homework tomorrow.
• We will look at the calculator stuff in class tomorrow which helps with this homework
• You must write a complete sentence and fully attempt the last two questions to receive hw credit!
• Tuesday HW (Due Thurs 10/17)
• Questions a, d, and e are all based on using your graphing caclulator!
• The instructions in your textbook are based on an older calculator (TI83), so if you have a newer (TI84) or a Casio calculator you'll have to google this and (maybe) watch a video
• Google: "how to create scatter plot on a _____"
• Google: "how to find correlation on a _____"
• Google: "how to find the linear regression equation on a ______"
• Or, watch AP Stat Guy Unit 2 Videos #1 and 2!
• The answer to question (C) on the key is not great...here's a better version:
• c.) The association between the number of stumps and the number of beetle larvae is positive, roughly linear, and moderately strong with r = 0.916; as the number of stumps increases, the number of beetle larvae increases.
• Need help with interpreting slope?
• Check out this AP Stat Guy Video about interpreting slope/y int!
• AP Stat Guy: Interpret Slope and YInt
• You must interpret slope/yint in a complete sentence to earn full credit!
• Homework answer key:
• Tuesday HW ANSWER KEY
• ALWAYS CHECK YOUR HOMEWORK ANSWERS! (CLICK THE LINK ABOVE!)

On Thursday in class we'll finish up chapter 7 with some notes about....

• Correlation 
• Lurking Variables
• Calculator stuff?
• We will have our chapter 7 vocab quiz next week (Mon or Tues). 

Then, on Friday, we'll start to get into chapter 8; see you there!

New Unit Tuesday + Weekend HW!

If you were absent yesterday today you must make up your test(s) on Tuesday, Thursday, or Friday of next week. You can do so after school Thursday or during any study hall/lunch any of those days.

• *I am not after school Tues or Fri, so if you have to do the test after school it must be Thursday

I hope you're feeling confident about your test! It was tough (and about 5 minutes too long), but I have confidence you'll improve from our first test.

Either way, here's the good news about AP Stat--new unit Tuesday! And new units in this class mean a fresh start; our next unit deals with scatterplots and association, which gives us all a clean slate with some (mostly) different content.

Homework(s):

1. The Unit 1 Progress Checks (MCQ Part B and FRQ) were intended to be used to study for your test. If you already took the test there is no need to do this. If you did not do the test then you should still look at these.

2. You must complete our next progress check in AP classroom--"Unit 2 Progress Check: MCQ Part A." This is due 

• This progress check will be counted as a classwork or quiz grade--and the grade will be based on your actual # of questions correct, NOT solely on completion
• This progress check gets into some new stuff; the first 9 questions deal with reading graphs and some two way table probability--the probabilities we have discussed
• Starting with question 10 you will start to see questions about scatterplots--this is new stuff for our new unit, so you may have to Google some things or use your textbook:
• Use the information below to help with the "new stuff." 
• Question 9: 
• A positive association means that as one variable increases, the other increases, or as x increases, y increases (graphically think of a positive slope)
• A negative association means that as one variable increases, the other decreases, or as x increases, y decreases (graphically think of a negative slope)
• Question 10:
• For help with describing shape/direction of scatterplots read the "Looking at Scatterplots" section on pages 143 to 144 of your textbook
• Questions 12, 13, and 14:
• All of these deal with understanding correlation
• Read (carefully) through the list of "correlation properties" on p. 152
• To learn more about correlation read the "Correlation" section starting at teh bottom of p. 146 to the step-by-step example on p. 150
• Question 15:
• For this question you need to calculate correlation
• DO NOT find correlation by hand
• Instead, use your graphing calculator!
• Google "how to find correlation on TI___" or "on Casio ___"
• Or, if you have a TI, you can look at the "TI Tips" yellow box on p. 151-152
• Question 16:
• This again deals with interpreting correlation
• It might be helpful to sketch a scatterplot that shows a negative correlation; label your x and y axes with the IV, DV, then use this picture to choose a multiple choice answer
• Question 17: 
• More correlation stuff....
• Back to reading about correlation in the book (see above)

Other than that, have a FANTASTIC four day weekend! Enjoy some time off, but also be sure to get this done! I'll see you on Tuesday for the next unit!