Differences between in-house and Intersection Magic data

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Differences between in-house and Intersection Magic data


The data in Intersection Magic is usually obtained from local city, county or state sources. In most cases, it is possible to query these sources to list the same data being reported by Intersection Magic. WeÕve found that when this is done, there may be discrepancies between the two systems. There can be several causes for these discrepancies. This document describes how we attempt to identify and resolve these differences when contacted by a concerned user of our software. While we welcome you to contact us, it is our hope that you can take the first steps yourself using the information provided here.




Identifying the problem

The most common problem is data appearing in Intersection Magic which doesnÕt show up in your in-house system; or data in your in-house system not showing up in Intersection Magic. In both cases, the first step is to identify which records are missing/added to the two systems. This usually takes the form of a case id list of the accidents in the study area in both systems.

In Intersection Magic, you can use “Reports / Listings / All accidents” to produce this list. With both lists in hand, do a manual comparison. What are the case id numbers missing from the shorter list?

Another possible problem is that data has different values for the same record in each of the two systems. We follow most of the same steps to resolve this problem. One added place to look in is your “import changes file” (???.cng). This file can be configured to change the values of data fields during the import process. Open this file using “Utilities / Edit config files / Import changes / Edit”. Check to see if the fields / values in question appear in this file.

The final possibility that this tech note will address is that of accident graphics that donÕt appear to represent the same data as appears in the in-house system. The first thing to do in this case is check for item (2) in this list. Click on the graphic in question and compare the field values to those in the in-house system. If the values match, then the problem is either with the configuration, or with our interpretation of your data.

If youÕre feeling ambitious, export and open your object table by selecting “Utilities / Edit config files / Object table / to ASCII” and then “edit”. This table, which is well documented in the manual, contains the ÔrulesÕ that Intersection Magic uses when generating each accident graphic.

If nothing is apparently wrong here, we will need to examine your data and configuration ourselves.

Get all the available information

Often, simply looking at the data provides the answer. Use “Edit / Open edit window” to open your ÔrawÕ ASCII source file. This editor can handle files of any size, although larger files can take several minutes to load. Use “Edit / Find” to locate the records which are in question. (Search for the case id number) Note the line numbers containing these records for later reference.

Things to look for

There are actually very few reasons why data discrepancies such as this may exist.

Street name misspellings. Intersection Magic groups accidents using street names. Even a minor misspelling indicates a different street to Intersection Magic. Check the records in your ASCII file to see if the street names are spelled the same in all cases. If not, consider using “Utilities / Database / Change streets” to fix the problem.

Bad dates. A record with a “bad date” can not be imported into the program. In this situation, the error is noted in the error??.log file. This file can be viewed by selecting “Edit / View log files”. If this file contains any mention of bad / missing dates, it will indicate the number of the offending line in the ASCII file.

Duplicate case id numbers. When a record is about to be added to the Intersection Magic database, its case id number is first checked against those already in the system. If the case id already exists, then the existing record is deleted prior to importing the new record. This prevents duplication. Again, look in the error??.log file. Duplicates will be noted along with the offending line number. This situation most often occurs when the police department recycles case id numbers each month or each year. The simple remedy for this situation is to pre-append the year or year and month to each case id number during the import process.

Accidents with missing data. When an accident record does not contain the data required to display it in the currently selected schematic, the program labels it as an “accident with missing data”. These accidents are displayed at the bottom of the diagram. Click on the accidents to determine which fields have missing data. (if the “accidents with missing data” section is not visible on the diagram, use Diagram / Configuration / Settings to choose “6 comments” instead of “key”.

Sending us data

When we are asked to identify the problem, the first thing we have to do to is to duplicate it on our system(s). This requires a data set identical to the one you are having the problem with. We also need to have a current version of your configuration. These can be sent to us by email / ftp / or conventional mail. When using an electronic means to send us the data, please use a zip program to compress and preserve the formatting of the data files. WeÕve found that often the process of attaching data files to email messages changes the structure of the data file. Using a zip program to compress the data prevents this from happening.

The data you send should include your configuration files as well as the raw ASCII data that you are importing. You should also include your “change streets” file if you are using one. Your configuration files are all of those with the following extensions: IMP, IML, IMS, LUS, LUC, TAB, TBS, CNG, DRD. There is no need to send your IM database files, as we will import your data fresh when we receive it. This also allows us to verify a working configuration. Also, please label any media you send with your Jurisdiction name and the date.

If you have PCAnywere running on your computer, and you provide us access to it, we can perform most of this analysis from our systems without requireing you to send us data

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