1. 6A Types of Data, 6E Measuring the Centre of Data
Unit 2: Descriptive Statistics
6A, 6E
2/24/ :33 PM

2. Statistics
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art of solving problems and answering questions by collecting and analyzing data Data can be … categorical: quality or characteristic quantitative: numerical value (“number of …”) discrete: exact number values (result of counting) continuous: within a continuous range (result of measuring) What category would the following variables fall under? score on a quiz methods of transportation students’ heights hair color
6A, 6E
2/24/ :33 PM

3. Common Terms
population: entire collection of individuals or characteristics under investigation census: collection of information from the whole population sample: subset of the population data: information from individuals in a population outliers: data values that are either much larger or smaller than the general body of data; should be included in analysis unless they are the result of human or other known error parameter: numerical quantity measuring some aspect of the population statistic: numerical quantity from a sample, usually used to estimate a population parameter
6A, 6E
2/24/ :33 PM

4. “Doing” Statistics
1. Identify the variable(s) of interest (the focus) and the population of the study. 2. Develop a detailed plan for collecting data. If you use a sample, make sure the sample is representative of the population. 3. Collect the data. 4. Describe the data using descriptive statistics techniques. 5. Interpret the data and make decisions about the population using inferential statistics. 6. Identify any possible errors.
6A, 6E
2/24/ :33 PM

5. Data Collection Methods
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observational study experiment simulation survey
6A, 6E
2/24/ :33 PM

6. Sampling Methods
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population sample simple random sample: every member of the population has an equal chance of being selected stratified sample: population is divided into groups (strata) and a random sample is taken from each group cluster sample: population is divided into groups (clusters) and select all of the members in one or more, but not all of the groups systematic sample: every kth member of the of population is chosen convenience sample: choosing members based on what is easy for the researcher
6A, 6E
2/24/ :33 PM

7. Measures of Central Tendency
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after collecting data, to measure the center: MEAN arithmetic average; is considered a “non-resistant” measure of center MEDIAN middle score (or average of the two middle scores) after data has been arranged least to greatest; is considered “resistant” MODE score(s) which occur most frequently two modes: bimodal three or more modes: not a measure of the center
6A, 6E
2/24/ :33 PM

8. Collecting Data
What’s your shoe size? Find the three measures of center for the set of data. Until we learn how to enter data into the GDC, you must show work by hand. What factors would impact the quality of our measures of center and what these statistical values represent? male vs. female shoe sizes universal shoe sizes text box vs. list of options What could we do to improve our analysis of the class’s “average” shoe size?
6A, 6E
2/24/ :33 PM

9. 6A, 6E
2/24/ :33 PM

10. Guided Practice
p. 160: 1(b)(d)(g)(i)(j)(l)(m) p. 172: 1,2,3(b),10,12,15,16 p.175: 1, 2  do not use the lists feature in your calculator. Read and follow all instructions. List the page and problem numbers alongside your work and answers in your notes. Use the back of the book to check your answers.
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6A, 6E
2/24/ :33 PM