STAT200 Study Guide - Summer 2018, Comprehensive Midterm Notes - Variance, Sampling Distribution, Confidence Interval
12 Oct 2018
School
Department
Course
Professor
STAT200
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Introduction
• Why should you be required to take statistics
o Voting behavior
o Medical research
o State of economy
o ^^ to make sense of all this data
▪ Most research depends upon the use of statistics to reach conclusions
• Just because you see something in your data, does’t ea it is so…
o In a sample, estimates could be wrong
• What is statistics?
o Science of data
o Refers to every aspect of how we handle/use data
▪ Collecting data
▪ Classifying, summarizing, organizing data
▪ Analysis of data using summary measure and graphs
▪ Interpretation of results
o Field of study and set of tools used by other disciplines
▪ Business and economics
▪ Social science
▪ Biological and physical sciences
• Descriptive statistics
o Uses summary measures, graphs and measures of association to help describe
the data or relationship in the data
o The focus is on describing the data
o With some emphasis on parsimony
▪ Notion in economy in the use of achieving something
• Inferential
o Is concerned with making inferences from a sample to a population
o Whenever we deal with a sample, we deal with estimates and uncertainty
o Helps us place our estimates in a probability framework that allows us to make
conclusions from data
o Powerful tool for research
o Enables us to make statements about large group from much smaller sample
▪ Survey
▪ Designed experiments
▪ Observational studies
Population samples and variables
• Population
o Total number of units involved in the research question
o The units are the members (elements) of the population
o Could be
▪ People
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▪ Animals
▪ Courses
▪ Objects
▪ Places
▪ Plants
▪ Etc.
o Populatio ad saple are defied y…
▪ Purpose of study
▪ Units and elements involved
▪ Geographic coverage
▪ Time frame
• Parameters vs. statistics
o A numerical summary measurement describing a population is called a
parameter
o A numerical summary measurement describing a sample is called a statistic
o Parameters are often represented by Greek characters
▪ (mu) is often used to represent the population mean
▪ X bar is used for the sample mean
• Census – collect data on all elements in population
• Sample – a subset of the units or elements of that population
o Saves time
o Saves month
• A valuable property of a sample is that is representative of the population
o By representative we mean the sample characteristics resemble those possess
by the population
o Cannot guarantee the sample will be representative, but if we select it on a
random basis we have a probability that will be representative
o Inferential statistics required a sample be taken on random basis
• Random sample
o When each element or unit has the same or nearly the same chance of being
selected
• Variable – characteristic of an individual unit of the population
o Ca’t all e the sae, otherwise it is a ostat
▪ Age of person in survey
▪ Height of plant in experiment
▪ Weight of package
▪ Gender of person in survey
• Measurement
o Process of assigning a number of characteristic to variable of the individual units
o Often complex
▪ Years of age
▪ Dollars of income
▪ Gender
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Introduction: why should you be required to take statistics, voting behavior, medical research, state of economy, ^^ to make sense of all this data, most research depends upon the use of statistics to reach conclusions. Just because you see something in your data, does(cid:374)"t (cid:373)ea(cid:374) it is so . In a sample, estimates could be wrong: what is statistics, science of data, refers to every aspect of how we handle/use data, collecting data, classifying, summarizing, organizing data, analysis of data using summary measure and graphs. Interview: face to face, telephone, self-administered, mail. Internet: observational studies, researcher observes units in their natural setting and records the variables of interest (must deal with a number of methodological issues, focus groups, studies of consumer behavior, wildlife studies in natural habitat. Initial digit in plot: helpful to look at range of variable to decide appropriate stems, add the leaves.
