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CrimeStat IV

Susan C. Smith

Christopher W. Bruce

Revised by: Thomas Mueller

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About CrimeStat PowerPoint

This PowerPoint was revised from the Susan C. Smith and Christopher Bruce’s work. The Original can be found at:
http://www.icpsr.umich.edu/CrimeStat/workbook.html

Their PowerPoint and Manual was developed for CrimeStat 3.0. This PowerPoints was revised for CrimeStat 4.0
The GeoTech Center wants to thank both of them for allowing us to use this tremendous resource.

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Chapter Two��Getting Data into (and out of) CrimeStat

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In Chapter Two...

File formats understood by CrimeStat
Projection and coordinate system considerations
Associating your data with values needed by CrimeStat
Accounting for missing values
Creating a reference grid
Measurement parameters
Getting data out of CrimeStat

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Introduction

Data must already be created, queried and geocoded
If your RMS or CAD automatically assigns geographic coordinates, you can import the data without going thru a GIS first
CrimeStat can read many formats, including .txt., .dat, .dbf, .shp, .mdb and ODBC data sources

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Introduction

No matter the format, for CrimeStat to analyze the data, the attribute table must contain X and Y coordinates

X and Y coordinates: X coordinate value denotes a location that is relative to a point of reference to the east or west and the Y coordinate to the north or south

Exception: ArcGIS ‘shapefiles’ which CrimeStat will interpret automatically and add the X and Y coordinates as the first columns in the table

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Introduction

Coordinate Systems

Longitude (X) and Latitude (Y) data (spherical coordinates)

Can be determined easily because the X coordinate will be a negative number (well, in North and South America)
If data is in this format, CrimeStat doesn’t need anything else
CrimeStat only reads long/lat data in decimal degrees (used by most systems)

U.S. State Plane Coordinates, North American Datum of 1983 (projected coordinates)

Specific to each state; based on an arbitrary reference point to the south and west of the state’ boundaries.
CrimeStat needs to know measurement units (feet/meters)

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Entering Your First Primary File (GIS Side)

Open basemap in ArcGIS Pro
Add burglary series shapefile
Check projection and coordinate system
Right Click on the Layer name – Properties and then choose Source Tab
Also check the map units
Then close ArcGIS Pro

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Primary File Screenshot

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Primary File Screenshot 2

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Entering Your First Primary File

Launch CrimeStat
Click Select Files

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Entering Your First Primary File

In Type: Choose Point Shape files
Click Browse

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Entering Your First Primary File

Choose the burglaryseries and click Open

Then Click OK

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Entering Your First Primary File (CrimeStat Screenshot)

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Entering Your First Primary File

Direct CrimeStat to X and Y coordinates using Dropdown menus

“The missing value column allows us to account for bad data by telling CrimeStat which records to ignore when it performs calculations on their coordinates. If we don‘t avail our-selves of this option, and some of our records have zeroes where the X and Y coordinates should be, all of our calculations will jump the rails. So, if even one of our 27 burglaries had zeroes in the coordinate fields, CrimeStat would put the mean center on a runway at Lincoln Municipal Airport—1.8 miles southwest of the mean center‘s actual location! Simi-lar problems plague zeroes and blank values of intensity, weight, and time.

Fortunately, we can account for several bad data types. The default is ―blank,‖ which will exclude blank fields and those with nonnumeric values. Most users should also automati-cally choose ―0.‖ (If you choose anything other than ―<None>,‖ CrimeStat will exclude blank fields in addition to whatever else you enter.) CrimeStat gives two other options in its drop-down menus (-1 and 9999), but users can also type directly into these fields, using commas to separate multiple values (so if –1, 99, 999 are missing value codes—along with blanks which are always excluded–you could type in those numbers in the missing value field). Note, however, that CrimeStat does not give you the option to choose a range of bad values, so if your bad data isn‘t consistent in its ―badness‖ (i.e., incorrect or missing val-ues have only a few possible codes), you may have to do a bit of data cleaning before you run CrimeStat. “ Bruce and Smith page 20

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Entering Your First Primary File

Select coordinate system and data units – remember the units in ArcMap were feet. So it is projected and feet

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Other Settings and Options

These are not required
Intensity – tells CrimeStat how many times to ‘count’ each point.

Default is to count each point once

Weight allows us to apply different statistical calculations to different points

Rarely used; but will see in a future chapter

Time is used in several CrimeStat space-time calculations

Must be input as integers or decimal numbers; will see in a future chapter

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Other Settings and Options

The missing value column allows us to account for bad data

Tell CrimeStat which records to ignore when performing calculations
Default is ‘blank’ which excludes blank fields and those with nonnumeric values
Users often choose “0”
Enter each missing value (-1, 99, 999)
Cannot enter ranges

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Other Settings and Options

Directional and distance fields are used if your data uses polar coordinate systems

This is rare

The secondary file screen allows us to enter a second file to relate to the first

Must use the same coordinate system and data units as the primary files
Cannot include a time variable

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Creating a Reference Grid

CrimeStat needs to know the extent of the jurisdiction
The reference file is a grid that sits over the entire study area

Can be imported or created by CrimeStat

To have CrimeStat create the grid

Specify coordinates of lower left and upper right extremities of the jurisdiction

Coordinates must be in the same system as the primary file

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Creating a Reference Grid

Select the Reference File tab; create grid
Enter values for Lower Left & Upper Right

Specify grid parameters

Either distance for each cell, or
Number of columns desired

Save ‘LincolnGrid’

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Creating a Reference Grid�(GIS Side)

Open ArcMap and add Streets and Burglary Series in ArcMap
Zoom into Burglary Layer
Move your cursor to the Lower left and write down the coordinates
Move your cursor to Upper Right and write down the coordinates
Put these coordinates into the Reference Grid (It may vary depending on cursor)

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Creating a Reference Grid (Lower Left)

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Creating a Reference Grid�(Upper Right)

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Measurement Parameters

Final bits of data for certain routines
Total area of jurisdiction (88.19 square miles in Lincoln)
Length of street network is the sum of all of the individual lengths of the streets (1283.61 miles in Lincoln)
The distance measurement tells CrimeStat how we want to see the distances calculated

Direct (as the crow flies), Indirect or Manhattan (along a grid) or Network (uses actual road network)

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Entering Measurement Parameters

Select the Measurement Parameters tab
Enter values for Area & Length of street Network
Choose “Indirect (Manhattan)” for type of distance measurement

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Entering Measurement Parameters (Area)

If you that information is NOT given then open ArcGIS Pro and add CityExt (City Extent)
Open the Attribute Table – Table Options
Add field

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Entering Measurement Parameters (Area)

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Entering Measurement Parameters (Area)

Choose a field name: SQMile
Dropdown – Float. Then Save

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Entering Measurement Parameters (Area)

Right Click on Field Name
Choose Calculate Geometry, Property = Area and Area Unit = Square Miles
Then Click Ok

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Entering Measurement Parameters (Area)

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Entering Measurement Parameters (Length of Street Network)

Complete previous steps for the streets layer
Field Name = Miles
Type = Float
Units = Miles
Save

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Entering Measurement Parameters (Length of Street Network)

Calculate Geometry
Miles and Length
Miles
Projection = Current Map

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Entering Measurement Parameters (Length of Street Network)

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Entering Measurement Parameters (Length of Street Network)

Select by Location
Input = Streets
Selecting Features = CityExt
Are within the source layer feature

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Entering Measurement Parameters (Length of Street Network)

Open Attribute Table
Choose Show Selected Records
Right Click on Miles
Click Statistics
Write down the Sum

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Entering Measurement Parameters

Select the Measurement Parameters tab
Enter values for Area & Length of street Network
Choose “Indirect (Manhattan)” for type of distance measurement

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Getting Data Out of CrimeStat

If the routine results in calculations for a number of records, it exports as a .dbf
If the routine results in one or more sets of coordinates, exports as

a .shp for ArcView
a .mif for MapInfo
a .bna for Atlas GIS boundary file