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Unit 1 Section 1.1 1-1: An Overview of Statistics What is Statistics? Statistics – the science of collecting, organizing, analyzing, and interpreting data in order to make decisions. Data – information coming from observations, counts, measurements, or responses. Section 1.1 Why study Statistics? Provides us the ability to read and understand various statistical studies. Provides us the ability to perform research and appropriately use data. Provides us the ability to become a better consumer and citizen. Section 1.1 Questions to think about this chapter… What are the branches of statistics? What is data? How are samples selected? Section 1.1 Data Sets There are two types of data sets we will utilize when studying statistics: populations and samples Population – collection of ALL outcomes, responses, measurements, or counts that are of interest. Sample – a subset (or part) of a population Section 1.1 Population vs. Sample Students at Eastern High School Students in Mr. R’s Prob/Stat Class Section 1.1 Example 1: Identify the population and the sample. The US Department of Energy conducts weekly surveys of approximately 800 gasoline stations to determine the average price of gasoline. On December 10, 2012, the average price of gasoline was $3.35 per gallon. Section 1.1 Parameter vs. Statistic Parameter – a numerical description of a population characteristic. Statistic – a numerical description of a sample characteristic. Section 1.1 Example 2: Determine if each numerical value describes a parameter or a statistic. A recent survey of approximately 400,000 employers reported that the average starting salary for marketing majors is $53,400. The freshman class at a university has an average SAT math score of 514. In a random check of 400 retail stores, the Food and Drug Administration found that 34% of the stores were not storing fish at the proper temperature. Section 1.1 Branches of Statistics Descriptive Statistics – the branch of statistics that involves the organization, summarization, and display of data. Inferential Statistics – the branch of statistics that involves using a sample to draw conclusions about a population. Inferential statistics often uses probability. Section 1.1 Example 3: Determine which part of the study represents descriptive statistics. What can you infer from the study? A large sample of men, aged 48, was studied for 18 years. For unmarried men, approximately 70% were alive at the age of 65. For married men, 90% were alive at the age of 65. Section 1.1 Descriptive vs. Inferential Descriptive Inferential Student test scores in this class Student test scores for all students in the next 10 years Memory spans of 30 subjects Memory spans for normal adults Homework Pgs. 6 & 7 (11 – 15, 21, 22, 25 – 29, 35 – 39) Read and take notes on Section 1.2 Pages Pg 9 – 12 in the text. 13 (1 – 6)