Category Archives: SL Topic 6: Statistics and Probability
SL: Statistics Study Guides
Study Guide 1 (due Mon. 10/1)
Click here to download the questions.
StudyGuide1AnswersSLStats (click to download the worked solutions)
Study Guide 2 (due Wed. 10/3)
Univariate Study Guide 2 Questions
Univariate Study Guide 2 Answers
Study Guide 3 (due Thurs. 10/4)
Univariate Study Guide 3 (Questions)
SL – 9/17/12 – 8.1 – Statistics Terminology
Click here to download another copy of today’s sheet (with the vocabulary words).
The vocabulary words are also below, with examples and links to other websites that might explain them better.
Word  Definition  Example 
1. Population  A collection of individuals about which we want to draw conclusions  e.g. all Americans, all IDEA Donna seniors 
2. Census  The collection of information from the whole population  e.g. Census 2010, the April ACT 
3. Sample  A subset of the population. (It is important to choose a sample at random to avoid biased results.)  e.g. every third house, 20% of each homeroom 
4. Bias  Misleading data, usually because a sample was not truly random  e.g. only counting seniors who took the ACT in December (might have a lower score than the overall average because they are retaking) 
5. Random Sampling  Choosing a subset of the population at random to avoid bias  e.g. setting quotas of each type of person, not just asking friends and family 
6. Survey  Collection of information from a sample  e.g. CNN polls asking 1,000 Americans who their preferred candidate is. 
7. Data (singular: datum)  Information about individuals in a population  e.g. I asked each person in 3rd period for one datum: his or her highest ACT score. When I put them in a list, I had data for 3rd period. 
8. Parameter  A numerical quantity measuring some aspect of a population. (As statistics are to samples, parameters are to populations.)  e.g. I estimated the whole grade’s average ACT score (parameter) by looking at my homeroom’s average (statistic). 
9. Statistic  A quantity calculated from data gathered from a sample. (Usually used to estimate a variable for the population)  e.g. mean ACT score, range of student heights in a homeroom 
10. Distribution  The pattern of variation of data.
Possibilities:

The distribution for SL’s Vectors Test is negatively skewed because the data looks flattened on the left of the mode. 
11. Outliers  Data much larger or much smaller than the general body of data. Include outliers unless they are a result of error.  Actual outlier: A police officer is measuring the speeds on 83. Most are going 70mph – then someone idles by at 45mph. Error outlier: I accidentally stepped on the scale while weighing my cat. 
12. Discrete Variable  A variable that takes exact number values. (Usually a result of counting)  e.g. number of people in a room, shoe size, date, number of rooms in a house 
13. Continuous Variable  A variable that takes number values within a certain range. (Usually a result of measuring)  e.g. height in cm, weight, temperature 
14. Frequency  The number of individuals in a survey who share a characteristic OR the number of times an event occurs  e.g. 6 people were late to 3rd period yesterday; 69,456,897 people voted for Obama in 2008 