Statistical Terms

LG: I can use proper statistical terms such as percentile and quartile to understand and analyze data

Prior Knowledge – Key Terms• Central tendency – Mean– Median– Mode

• Try This! Investigate– Organizing and Describing Data– Pg. 196

These Are The 10 Most Unequal Cities In America

“The study from the Brookings Institution looks at the "95/20 ratio" for the 50 largest cities in 2012--the difference between 95th percentile and 20th percentile income.

Atlanta comes out worst with a 18.1 ratio. In Atlanta, a household in the top 5% earns $280,000 each year and the bottom 20% gets $15,000.”

Percentile

A percentile tells approximately what percent of the data are less than a particular value.

Example: Using PercentileThe math test scores in a class of 20 were: 50, 65, 70, 72, 72, 78, 80, 82, 84, 84, 85, 86, 88, 88, 90, 94, 96, 98, 98, 99

1. If Bobby scored an 86% on the test, find his percentile rank.

2. If Daniel scored in the 76th percentile, what was his mark on the test?

'Marriage gap' exists between wealthy and poor Canadians, report concludes

“According to the Institute of Marriage and Family Canada, 86 per cent of the highest income quartile are married or have a common-law spouse. Forty-nine per cent of those in the middle-income quartile are in a relationship, while 12 per cent of the lowest-income quartile is in a relationship.”

Quartile

• Quartiles are three numbers that separate data into four equal parts when values are list lowest highest.– The middle quartile (Q2) is the median of all the data

– The first (Q1) quartile is the median of the data values less than the middle quartile.

– The third (Q3) quartile is the median of the data values greater than the middle quartile.

Example: Determine the QuartilesData Set: 1, 3, 3, 4, 5, 6, 6, 7, 8, 8 1. Order from smallest biggest (The numbers are already in

order)

2. Cut the list in half to find Q2 (median)In this case Quartile 2 is half way between 5 and 6:Q2 = (5+6)/2 = 5.5

3. Cut the halves in half to find Q1 and Q3:Quartile 1 (Q1) = 3Quartile 2 (Q2) = 5.5Quartile 3 (Q3) = 7

1, 3, 3, 4, 5, 6, 6, 7, 8, 8

Q2Q1 Q3

Homework

• Pg. 201 # 1, 3, 8, 9, 12, 14