# Units of Analysis and data structure - PowerPoint PPT Presentation

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## Units of Analysis and data structure

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### Units of Analysis and data structure The Basics * We are going to spend some time today reviewing the importance of the unit of analysis in the statistical and data ... – PowerPoint PPT presentation

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Title: Units of Analysis and data structure

1
Units of Analysis and data structure
• The Basics

2
Outline
• Definitions
• Elements of the unit of analysis
• Data structure

3
Unit of observation
• The unit of observation is a basic concept in
quantitative research that represents the objects
that are observed and about which information is
systematically collected.

4
Unit of analysis
• The unit of analysis is the object about which
generalizations are made based on an analysis.

5
Determination
• The unit of observation is determined by the
method by which observations have been selected
• The unit of analysis is determined by an interest
in exploring or explaining a specific phenomenon.

6
When they are the same
• The unit of observation and unit of analysis are
the same when the generalizations being made from
a statistical analysis are attributed to the unit
of observation.

7
Identifying units of analysis
• The unit of analysis is shaped by three
properties
• Social entities
• Time
• Space

8
Social entities
• observations of a single social entity, such as a
person or an institution
• observations of multiple entities with a defined
relationship, such as family, employer-employee

9
Social Phenomena
• transactional observations that are the result of
actions among entities, such as labour strikes or
international conflicts, including wars.

10
Time
• observations made at one point in time a
cross-sectional study

11
Time
• observations made at multiple points in time
• the data may be organized by time commonly
referred to as a time series
• time may structure some form of repeated measures
of content or subjects

12
Space
• observations made within a specific spatial area
• observations made within a hierarchy of spatial
areas

13
Substituting units
• There may be requests for which data for a
desired unit of analysis cant be delivered but
for which data are available summarized over one
of the other attributes of the unit of analysis.

14
Substituting units
• Example
• Request for firm-level data for NAICS 312
Beverage and Tobacco Product Manufacturing
• Ideal source microdata on establishments from

15
Substituting units
• Example NAICS 312
• Alternatives are there aggregate data
summarizing the firms within NAICS 312?
• Possibilities summaries over time (time series)

16
Statistical data structure
• Lets review basic data structure.
• The unit of analysis defines the underlying
structure of a data file.

17
Statistical data structure
• This structure consists of a series of rows with
each row containing the data of one member of the
unit of analysis.
• This simple structure is known as the flat,
rectangular data matrix.

18
Statistical data structure
Case n-1
19
Statistical data structure
• All of the information collected for each member
of the unit of analysis is organized in a fixed
location in the file called fields or variables.

20
Statistical data structure
Case n-1
21
Statistical data structure
22
Statistical data structure
• This structure looks like the grid of a
spreadsheet. However, there is one very
important difference between a statistical data
• The spread sheet is organized around individual
cells, while the statistical data structure is
organized around the rows.

23
Statistical data structure
24
Statistical data structure
Cell B2
Cell E3
Cell C5
Cell F7
25
Statistical data structure
Statistical Data Structure
Row 1
Row 3
Row k-1
26
Statistical data structure
• The next slide presents the way that this simple
statistical data structure appears in SPSS.

27
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28
Row 1
29
Row 8
30
Row 8
Row 15
31
Field 8
Row 8
Row 15