 Observations that you or someone else records  Data is more than numbers; it is numbers in context  Data isn’t only numbers; it is also the story behind the numbers

 Talk for 30 seconds and then share out  News media; surveys galore!  Any recent news report (based on survey or poll) that you can recall? Radio? TV? Internet?  Recent survey showed that of the people who use Twitter and Facebook, more are likely to get their news from Twitter than Facebook  More than half of Jewish students at American colleges reported personally experiencing or witnessing anti-Semitism within the past six months, according to survey findings.

 Variables record characteristics of people or things  # people in the survey who said they get their news from Facebook primarily (or Twitter primarily)  # of Jewish college students who were (or were not) observing or experiencing anti- Semitism

SampleStatistic (changes from sample to sample; can vary) PopulationParameter (is fixed; does not change) Examples include µ, p, σ

 Always, always comment, answer, compare, contrast… whatever the case.. in context  What are the objects? What was measured? What are the units of measure?  Example… Researchers studied the amount of tofu, in pounds, that a typical American consumes per year.

 Who carried out the survey?  How was the sample selected?  How large was the sample?  What was the response rate?  How were the subjects contacted?  When was the survey conducted?  What was the exact question asked?

 Come up to board and write where you last went out to eat and how much you spent there (approximately).  What are our variables?  Two types of variables: Numerical (quantitative) and categorical (qualitative)  Which is which for our data?

 Can you think of a categorical data that looks like numerical data… but it isn’t. It’s really categorical. Discuss with your group for a minute…  Zip codes, social security numbers, phone numbers, student ID numbers, etc.  Always ask yourself, does finding the mean (average) of this data make sense?

 Come up to the board and write yes if you have pierced ears and no if you don’t. Use a blue marker if you are male; use a black marker if you are female.  What trends do you see?  Hard to clearly see trends when data is not organized  One common way to organize categorical data is in a 2-way table

Ears PiercedEars NOT Pierced Male Female

 Suppose on a given day we randomly ask 200 Disneyland visitors if they have been on Space Mountain yet that day.  23% said they had been on Space Mountain already. How many of these visitors had been on Space Mountain already?  46 of these Disneyland visitors had already been on Space Mountain.

 Suppose we randomly ask another group of Disneyland visitors if they have been on Thunder Mountain yet that day. 14% tell us yes, and this is equal to 42 visitors.  How many total visitors were in our survey?  300 visitors were asked if they had been on Thunder Mountain yet that day.

SportInjuriesParticipants Baseball178,66815,600,000 Basketball615,54628,900,000 Bowling21,13343,900,000 Football387,94817,700,000 Ice Hockey16,4352,100,000 Soccer178,51914,500,000 Softball125,87513,600,000 Tennis19,63311,000,000 Volleyball59,22511,500,000

 There are always firefighters at fires. Therefore, firefighters cause fires  x: Person regularly attends religious services  y: How long a person lives  x: Number of ministers  y: Rum imports  x: HS seniors’ SAT scores  y: Students’ first year GPA

 x causes y, there must be a controlled, randomized, well-designed experiment  Treatment (explanatory, factor) variable; Response (outcome) variable  Sample size ‘large’  Treatment group (receiving treatment(s); control group (receiving placebo)  Random assignment of subjects (or experimental units)… using an acceptable randomization process  Double-blinding is best

 Reduce bias  Bias: Systemically ‘off’  Examples: scale, clock

Gastric freezing is a proposed treatment for ulcer pain in the upper intestine. In this treatment the patient swallows a deflated balloon with tubes attached. Then a cold liquid is pumped through the balloon for an hour. The rationale is that the cooling will reduce production of acid and relieve ulcer pain. A study reported in the Journal of the American Medical Association provided gastric freezing to a large number of patients and reported that gastric freezing reduced acid production and relieved stomach pain. Based on this the (safe and easy) treatment was used for several years.

A later study divided ulcer patients randomly into two groups. The first group was treated by gastric freezing. The second group received a placebo treatment in which the liquid was at body temperature rather than cooled In the first group 34% of 82 patients improved. In the second group 38% of 78 patients improved. Based on this second study gastric freezing was discontinued as a therapy for ulcers.

 Is it well designed? Why or why not?  Marshmallow video

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 Is this an observational study or a controlled experiment?  Experiment? Was there a large sample size? Was randomization used to assign participants to treatment groups? Was the study double- blinded? Was there a placebo?  Was the paper published in a peer-reviewed journal or just posted on internet?  Did the study follow the subjects for a long period of time?

 We will randomly assign you into partners  Minitab – calc – random – integer  Move to sit next to your partner

 You and your partner create a list of a total of 3 questions we may use for a survey (data we may collect) this semester; be specific; be “G” rated  Next to each question, write the type of data your question is asking for (categorical or numerical) and justify why it is that type of data  Example: What do you weigh in pounds? This is quantitative data.  But both your names on the paper; write neatly