GTECH 201

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GTECH 201

• Lecture 03Data measurementsData errors

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Measurement

• The process of obtaining scores for each element
  for each variable
• This can take on a variety of forms
• Producing scores (and distributions) of a widely
  varying nature
• The measurement of raw variables
• Derived variables and measurement
• Measurement of the time component
• Measurement of the space component

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Measurement of Raw Variables

• Primary and secondary data control over the
  measurement process
• Operational definitions of the measurement
  process
• Highly varied terminology for the different
  levels of measurement

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Derived Variables and Measurement

• Why not use raw variables?
• Derived variables can be considered as a ratio
  (or percent or index) of two numbers the
  numerator and the denominator (in the ratio a/b,
  a is the numerator, b is the denominator)

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Measurement of the Time and Space Components

• Time is a continuous variable
• Date, time and datetime
• Space is a continuous variable
• (x,y) and (x,y,z) location measurement
• Distance and bearing alternative

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Measurement Scales
Most statistical texts follow the original 4-fold
measurement structure attributed to a chap
called Stevens, written up in 1946

• Nominal
• Ordinal
• Interval
• Ratio

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Geographical Data

• Dayta or darta
• Data sets used by geographers
• Geographic vs. spatial data
• 3 Quick Questions
• What would a piece of data look like?
• Must data consist of numbers?
• What would a data set look like?

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3 Approaches to Data Definitions
The terminology used in handling data sets (in
geography) stems from three different sources.
It is now somewhat of a mix of the three.

• Statistical analysis
• Spatial analysis
• Data base structures (IT)

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Some Basic Definitions

• Element ( observation entity) the smallest
  (measurable) unit
• Population (of elements) (approximately equal to
  universe) the totality of all elements. May be
  finite or infinite, with size known or unknown
• Sample a subset of the population
• Variable ( attribute) a characteristic of the
  element in which we are interested
• Data score (or simply datum/data) an individual
  value for an element for a variable
• Data distribution a set of scores for a
  variable
• Data set an assemblage of related data
  distributions for a set of elements

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Things We Can Do With Data

• Data display a display of a data distribution
  in the form of a table, graph or map
• Data analysis the analysis of data
  distributions (including statistical analysis)
• Data storage and retrieval just as the name
  implies (anything from sheets of paper in a
  folder to a computer file)

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Data Structure

• Measurement is the process of obtaining scores
  for an element
• Each element will have an infinite number of
  characteristics, the relevant ones of which will
  be measured (the variables or attributes)
• The element will also occupy a locational
  position in time and space sometimes this
  position is important, sometimes it is not

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Geographic Data Structure

• A generalized data structure for each element is
  
• The data structure that results can be presented
  (stored) in a data matrix, where the columns are
  the variables (with or without the temporal and
  spatial location), and the rows are the elements

(var1, var2, .., vark), (temporal location),
(spatial location)
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Introduction to MS Excel

• Opening screen

• Typical look of an Excel spreadsheet

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User Interface Elements

• Title bar
• Menu bar
• Toolbars
• Standard toolbar
• Formatting toolbar
• Formula bar
• Status bar

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Worksheets
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Name Box
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Selecting Cells
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Entering and Editing Data

• Entering Data
• Editing Data
• F2

• Double-click

• Formula

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Formatting Text

• Just as in MS Word
• Alignment
• Bold, italics, underline
• Font color

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Column Width

• Choose Format gt Column gt Width  
• Drag cursor on separation line
• Double click on separation line
• Holding left mouse pressed

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Moving to a New Worksheet
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Mathematical Calculations

• Cell arithmetic
• AutoSum
• Function button

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Functions

• Function categories
• Function wizard

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Formatting Numbers

• Choose Format gt Cells  
• Before
• Toolbar

• After

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Deleting Rows and Columns
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Creating Borders

• Choose Format gt Cells 
• Border icon on toolbar

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Merge and Center

• Icon on Formatting toolbar
• Autofill

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Printing

• Page setup or Print preview

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Creating Charts

• Step 1 - select the data that you want charted
• Step 2 pull-up chart the wizard

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Modifying Charts

• Change size and position
• Modify other characteristics