Bivariate Data

1. Bivariate Data Learn to set up bivariate data in tables and calculate relative frequencies.

2. Vocabulary: • Categorical Data – data that is in two distinct groups • Male & Female • Has siblings & Does not have siblings • Republican & Democrat • Has chores & Does not have chores • Bivariate – data for two variables

3. Thirty students were surveyed to see if they play sports or play an instrument. The data was organized as shown below. Copy this table into your notes. What can you conclude from this data?

4. Change to percents… • We can find relative frequencies by changing the data to percents. • Divide male sports by it’s row total (12/15 = .8) • Divide male instruments by it’s row total (3/15 = .2) • Divide the male row total by the column total (15/30 = .5) • Repeat process for the rest of the rows. What can you conclude from this data?

5. Rewrite the values of the table as relative frequencies. Add up each row. Add up each column. Divide siblings yes pets yes by the row total (32/54 = .59) Divide siblings yes pets no by the row total (22/54 = .41) Divide siblings no pets yes by the row total (27/46 = .59) Divide siblings no pets no by the row total (19/46 = .41) Change row totals to percents.

6. What can we learn from the data? • We learned that the majority of the people surveyed who had siblings. • We learned that you were just as likely to have a pet if you had siblings and if you didn’t have siblings. • We learned that the majority of the people surveyed had a pet.