View
57
Download
0
Category
Tags:
Preview:
DESCRIPTION
Z 519: Information Analytics. Social Statistics: Introduction. Social Statistics. Statistics describes a set of tools and techniques for describing, organizing and interpreting information or data. Do we need statistics? When and Why?. Why we need statistics. - PowerPoint PPT Presentation
Citation preview
Z519: Information Analytics
Social Statistics: Introduction
Statistics describes a set of tools and techniques for describing, organizing and interpreting information or data.
Do we need statistics? When and Why?
Social Statistics
Everybody relies on data in one way or another: corporate presidents decide company policy
based on quarterly sales figures politicians decide on campaign strategy based
on polls teachers decide grading curves based on a bell
curve you and I decide whether to smoke or not
based on health records of other people Therefore, we need a comprehensive and
understandable way to deal with data: Statistics is the study of making sense of
data.
Why we need statistics
Asking the research question Formulating the hypotheses Collecting data Analyzing data Evaluating the hypotheses
The research process
Questions What factors affect the economic mobility of female
workers Do male and female use twitter differently?
Hypothesis A relationship between two variables Variable is a property which can take two or more values Unit of analysis: individual, group, organization, nation Dependent variable: the variable the researcher wants
to explain (the “effect”) Independent variable: the variable that “cause” or
account for the dependent variable Gender cause wage difference (gender: is independent variable,
wage difference is dependent variable)
The research process
What are independent and dependent variables Younger Americans are more likely to support
stricter gun control laws than older Americans People who attend church regularly are more
likely to oppose abortion than people wo do not attend church regularly
Elderly women are more likely to live alone than elderly men
Individuals with postgraduate education are likely to have fewer children than those with less education.
Independent vs. dependent variables
Cause-and-effect relationship The cause has to precede the effect in
time There has to be an empirical relationship
between the cause and the effect This relationship cannot be explained by
other factors.
Causation
Used to organize and describe the characteristics of a collection of data
Descriptive statistics
How can you describe this table?
Descriptive statistics
Name Gender
Major Age Score
Sara Female LIS 27 A
Richard Male Psychology 30 C
Andrea Male Education 33 B
Emily Female Language 25 B
Bill Male LIS 28 C
Leo Female Psychology 26 A
Liz Female LIS 26 B
Alice Female LIS 28 C
Steven Male Psychology 24 C
Jeff Male LIS 30 B
Make inferences from a smaller group of data to a possible larger one Sample: a smaller group of data Population: the whole group of a certain
subject
Inferential statistics
population the set of all photographs of Mars the set of heights of people in the US Army the set of all measurements of water quality taking from
the Lake Monroe the set of all problems that can be solved using statistics.
sample the pictures selected from a specific region of Mars the heights of people in a particular division of the US
Army the set of water measurements of the Lake Monroe taken
on 1/12/2015 the statistical problems we are solving in this class
Population & Sample
Problem definition what is the population of interest, and what are the variables that are to be investigated
Data collection describe and select the sample from the population
Data analysis make some statistical inferences from the sample about the population
Analysis Reporting report the inference together with a measure of reliability for the inference where we use the term variable to mean a characteristic or property of an individual population where the observations can vary.
Steps for statistical analysis
Example: A tax auditor is responsible for 25,000 accounts. How many accounts are in error?
Defining the problem: The entire population consists of all 25,000 accounts. Our goal is to obtain a reasonable estimate for the number of accounts that are, in all likelihood, in error. Our variable x counts whether an account is in error.
Data collection and summary: The auditor decides to select 2000 accounts at random, tests each of these, and finds that 84 of them are in error.
Data analysis: In this case, the likely theory involves computing 84/2000 = 4.2%.
Analysis reporting: Based on our data analysis we infer that approximately 4.2% of the accounts will be in error.
An example
Excel Excel Toolpak SPSS/PASW
Tools
1. Click the green File tab, and then click on Options.2. Click Add-Ins, and then in the Manage box, select
Excel Add-ins.3. Click Go.4. In the Add-Ins available box, select the Analysis
ToolPak check box, and then click OK. 5. If you get prompted that the Analysis ToolPak is not
currently installed on your computer, click Yes to install it.
6. After you load the Analysis ToolPak, the Data Analysis command is available in the Analysis group on the Data tab.
Excel Toolpak (1)
Powerful, reliable, accessible, easy, and free
Excel Toolpak (2)
Operator Symbol Example What it does
Addition + =2+5 Adds 2 and 5
Subtraction - =5-3 Subtracts 3 from 5
Division / =10/5 Divides 10 by 5
Multiplication * =2*5 Multiplies 2 times 5
Power of ^ =4^2 4 power of 2
Formula
How does it work in Excel?
So let's get started digging into what makes a spreadsheet work. Spreadsheets are made up of: columns Rows cells
In each cell there may be the following types of data: text (labels) number data (constants) formulas (mathematical equations)
Basics of a Spreadsheet
Column
Row
Cell
data types examples descriptions
LABEL Name or Wage or Days
anything that is just text
CONSTANT 5 or 3.75 or -7.4 any number
FORMULA =5+3 or = 8*5+3 math equation
Types of Data
ALL formulas MUST begin with an equal sign (=).
The Sum function takes all of the values in each of the specified cells and totals their values. The syntax is: =SUM(first value, second value, etc)
Formulas – SUM
The average function finds the average of the specified data. The syntax is as follows =Average(first value, second value, etc.)
Formulas – AVERAGE
MAX: This will return the largest (max) value in the selected range of cells.
MIN: This will return the smallest (Min) value in the selected range of cells.
Formulas – MAX/MIN
This will return the number of entries (actually counts each cell that contains number data) in the selected range of cells.
Formulas – COUNT
Recommended