Intro to Statistics Chapter 1 Notes
Intro to Statistics Chapter 1 Notes STAT 145
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This 7 page Class Notes was uploaded by Michaela Zerbo on Tuesday September 6, 2016. The Class Notes belongs to STAT 145 at Rochester Institute of Technology taught by Professor Nilay Sapio in Fall 2016. Since its upload, it has received 178 views. For similar materials see Intro to Stats in Statistics at Rochester Institute of Technology.
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Date Created: 09/06/16
1 STAT 145 Introduction to Statistics 1 Chapter 1 Data Collection Terms ormulas 1.1 Introduction to the Practice to Statistics Objectives: Definitions and process of statistics / Qualitative vs. Quantitative Statistical Process: Population: An entire group of people, things, or events that has at least one common trait. Sample: A smaller number of observations taken from a population Parameter: A measure obtained from the entire population. This is not practical. Parameters, the value related to P pulations What we want Statistics: A measure obtained from the sample. Statistics, the values pertaining to Samples What we get 2 Variables: Quantitative (Numeric): Provides numerical measures of individuals Discrete vs. Continuous Interval: Ordered categories with meaningful difference in values (no true 0) Ratio: Interval measurement with meaningful ratio of values (0 means lack of quantity) Nominal: C ategories Names Titles Ordinal: Ordered categories Examples: Hair Color Nominal Country N ominal Value of a Liquid Ratio Men’s Clothing Size Ratio/Interval/Ordinal depends how view Degree O rdinal 3 Which is better? It depends. Observation is more cost and time effective Experimental can identify causal relationships 1.2 Observational Studies vs. Designed Experiments Objectives: R ecognize different types of studies 4 1.3 Introduction to the Practice to Statistics Objectives: U nderstand a simple, random sample 1. Sample: Students sitting in the last row / Population: All STAT 145 students 2. Sample: First 200 customers arrived in a stadium / Population: Stadium customers 3. Sample: Students taught in room 145 / Population: All RIT students 4. Sample: People in Costco / Population: New York Public Random Sampling: Random Sampling: Selecting individuals from a population through chance Simple Random Sampling: As if every member of the sample has an equal chance of being picked How do I obtain a Simple Random Sample? 5 1.4 Other Sampling Methods Objectives: Understand a stratified, systematic, and a cluster sample Stratified Sample: ● Separate population into a nonoverlapping group called Strata ● Obtain simple random sample from each stratum ● Individuals in each stratum should share similar attributes Systematic Random Sample: ● Select a number (x) ● Randomly select a number between 1 and x ● Survey every x thindividual until desired sample size Cluster Sample: ● Randomly select a collection/group ● Include all individuals in the selected group for the sample Convenience Sample: ● Individuals are easily obtained ● Not random Unreliable results ● Sample is not representative Multistage Sample: ● Use a combo of sampling methods 6 Examples: 1. To determine the customer opinion of its customer service response, Cosco randomly selects 3 days during a certain week and surveys all customers in register 5. (Cluster) 2. To understand the utilization of the No Voice Zone, RIT randomly selects 150 students using its roster. (S imple Random) 3. Starbucks selects every 6th customer that walks through until they obtain the views about their new coffee display. (Systematic Random) 1.5 Other Bias in Sampling Objectives: Understand the source of bias The Three Sources of Bias: 1. Sampling Bias: Sampling techniques used tends to favor one part of the population over another Ex. Public opinions polls done through phone calls may excluded those without a home phone or those who are homeless. 2. Nonresponse Bias: What happens when individuals selected in the sample who do not respond have different opinion than those who respond? FollowUps 7 3. Response Bias: When the answers do not reflect the true feelings of the respondent HOW? 1. Interview error 2. Data entry error 3. Wrong wording 1.6 Design of Experiments Objectives: Characteristics of Experiments Experiments are a controlled study that determines the effects of factors on a response variable.