Todays Brainteaser

1
Todays Brainteaser

• A woman had two sons who were born on the same
  hour of the same day of the same year. But they
  were not twins. How could this be so?

2
Note 1.1 The four sampling methods

• Cluster Sampling
• A sample chosen by picking special groups or
  clusters of people
• Say Cluster together like a neighborhood or a
  team
• Examples
• Choosing areas of a city, or neighborhoods
• Choosing to poll the football team, basketball
  team, etc.
• Polling the first group of ten people who enter
  the door

3
Note 1.1 The four sampling methods

• Systematic Sampling
• After a population is ordered in some way, the
  sample is chosen according to a pattern
• Say Systematically pick every 1st, every 2nd,
  every 3rd, every 4th.
• Examples
• Selecting every tenth item from a list
• Polling every 5th person who walks by
• Calling every 20th phone number in the phone book

4
Note 1.1 The four sampling methods

• Random
• Each member of the population has an equal chance
  of being selected. The members are chosen
  independently of each other.
• Say Randomly pick names from a list
• Examples
• Put 100 names in a hat and randomly pick out ten
  names.
• Randomly select names from the class list

5
Note 1.1 The four sampling methods

• Convenience
• The sample is chosen only because it is easily
  selected.
• Say Its convenient to ask people next to me or
  my friends.
• Examples
• Poll the 10 students who happen to be standing
  next to you in the cafeteria line
• Poll your friends at school

6
Identify the method. List advantages and
disadvantages of the method.

• In an assembly line, every twentieth rowing
  machine out of 500 is quality tested. Two are
  defective.
• What kind of sampling method does this situation
  represent?
• What might be an advantage of this kind of
  method?
• What might be a disadvantage of this kind of
  method?

7
Identify the method. List advantages and
disadvantages of the method.

• Answers
• In an assembly line, every twentieth rowing
  machine out of 500 is quality tested. Two are
  defective.
• What kind of sampling method does this situation
  represent? Systematic
• What might be an advantage of this kind of
  method? You are sampling from the whole
  population
• What might be a disadvantage of this kind of
  method? You might miss defective machines that
  werent sampled

8
Identify the method. List advantages and
disadvantages of the method.

• You want to figure out what the most popular
  video game is. You poll the first 12 people who
  you meet in a video-store.
• A. What kind of sampling method does this
  situation represent?
• B. What might be an advantage of this kind of
  method?
• C. What might be a disadvantage of this kind of
  method?

9
Identify the method. List advantages and
disadvantages of the method.

• Answers
• You want to figure out what the most popular
  video game is. You poll the first 12 people who
  you meet in a video-store.
• A. What kind of sampling method does this
  situation represent? Convenience
• B. What might be an advantage of this kind of
  method? The entire population sample is
  guaranteed to like/play video games
• C. What might be a disadvantage of this kind of
  method? Polling only 12 people may not give an
  accurate survey result

10
Last Question

• Which reflects the random sampling method that
  might be used to identify the types of books that
  are most popular among high school students?
• Choose 20 high schools at random around the U.S.
  and poll EVERY student there.
• Give questionnaires one day to all high school
  students who visit the Lincoln Memorial on class
  trips to Washington D.C.
• Dial phone numbers at random around the country
  and ask to speak to a teenager.

11
Mix-N-Match

• Hands up and Pair up. HIGH FIVE your partner
• Partners quiz each other.
• Say Thank you for sharing
• Partners trade cards.
• Students quiz new partners.
• Teacher calls FREEZE
• Students MATCH the vocabulary word with an
  example
• Students who MATCH up must go stand on the
  perimeter of the room, forming a circle.

12
Work on Homework Assignment

• Due next class period
• Label the top of your paper
• 1.1 Pages 8-9 11-23, skip 16
• Write your name on the top of the paper.
• Use PENCIL whenever you are doing homework.
• You may discuss and get help from your team. If
  nobody in your team knows or can help you, Hold
  up your team sign for the teacher to see.

13
Team Interviews

• Spin the spinner to see which person gets
  interviewed 1st.
• That person STANDS UP to be interviewed.
• Each teammate draws and reads one question to be
  answered.
• After the interviewee answers all the questions,
  they may sit down and the next teammate stands up
  to be interviewed.
• Make sure you speak clearly and loudly enough to
  be heard!