1. Statistics Population/Sample Survey

2. Statistics Practice of collecting and analyzing data to make future decisions. For example, Lays Potato Chips offers a wide variety of flavors http://www.fritolay.com/our-snacks/lays.html Using sampling methods Lays surveys its population to determine which flavors will continue to be sold.

3. Population Every element in the universe of interest ; all the possible football teams

4. Sample A subset of the population ; NFC East

5. Survey Question asked of the sample group. Who will win the Super Bowl?

6. Statistics is fun! Population – every element in the universe of interest Sample – a subset of the population Survey – question asked of the smaller group

7. Kinds of Samples Statistics is still fun

8. Random – Choose your population - 7 th graders/7 th grade teachers/7 th grade parents. – Put all the names in a hat and draw out 20 – this is your sample. – Each is chosen by chance to answer the survey question. – Considered unbiased because everyone has an equal chance of being chosen. Is the BGT a good field trip for the 7 th grade?

9. Stratified Random – Same population divided into groups based on a common theme (7 th grade students, 7 th grade teachers, 7 th grade parents). No overlapping between groups No group excluded – Draw out 20 names from each group – this is your random sample to answer the survey question. – Considered unbiased because everyone still has an equal chance of being chosen but every subgroup is included. Is the BGT a good field trip for the 7 th grade?

10. Cluster - Same population divided into groups based on a common theme (7 th grade students, 7 th grade teachers, 7 th grade parents). -Randomly pick one group. Everyone in the subgroup is included. This is your sample that will answer the survey question. -Considered biased because you have excluded two groups. Is the BGT a good field trip for the 7 th grade?

11. Systematic Random – Same population - 7 th graders/7 th grade teachers/7 th grade parents. – Sample is based by choosing every ‘nth’ person. For example, every 8 th person will answer the survey question. – Still random but more constraints. – Considered biased because one subgroup might be over or under represented. Is the BGT a good field trip for the 7 th grade?

12. Convenience – Same population - 7 th graders/7 th grade teachers/7 th grade parents. – Sample is based on the individuals that are easiest to reach. For example survey question is asked during 1 st lunch in the US cafeteria or during the 7 th grade parent potluck dinner. – Considered biased because one subgroup almost certainly will be over or under represented. Is the BGT a good field trip for the 7 th grade?

13. Voluntary Sample – Same population - 7 th graders/7 th grade teachers/7 th grade parents. – Individuals choose to respond to the survey question. This is your sample. – Considered biased because people with strong opinions respond. Is the BGT a good field trip for the 7 th grade?