Common Mistakes that will Drastically Reduce Your Stress Level if you can Avoid Them

Class/Lecture Tips

  • Pay attention! Resist the urge to go onto Facebook or email. These labs go full force and it’s really easy to get lost even when you are fully focused.
  • Print out the labs before class and read them over. If you get stuck, look at the lab directions, then try asking someone next to you, then raise your hand. It’s better to get all the way through the lab than to get bogged down in the details- even if it means you need to re-read the directions/justifications after class.

General Tips

  • Have a File Organization and Naming System
    • You are going to be making a million shapefiles and lots of them are not going to be what you can use either because they don’t work or it doesn’t have all of the data you need on it
    • So, when you have LACity shapefile, and then you clip it, name it something like LACity_2, that way you know that the shapefile you need to use is the highest numberedT
  • You have that red exclamation sign next to some of your data
    • That’s ok. Just right click, go to data, go to repair data source, and find where you saved the shapefile or spreadsheet and click.
    • Sometimes this happens because you didn’t store relative pathnames when you saved your map, so remember to check and do that!
  • Make sure that after you join, you export the join.
    • This is the only way you can use your join other than look at it in the attribute table
    • Exporting will create a NEW shapefile with both of your files combined
  • SAVE your work. Constantly.

Midterm Project Tips

  • Use the lab instructions, but don’t be paralyzed by them
  • In the lab, you had ready-made data. For your midterm you will be using whatever you pull from other places, which means that you have to prepare it by yourself before it is GIS ready. Try to get your data to look like the lab data, but it’s ok if it is a little different.
  • Google it! Sometimes you have to go through a couple of links, but it can be helpful.
  • You added an excel sheet (census data or something) and when you open it is has <null> or no values, or it simply won’t do what you want it to
    • Go back to your saved document, make sure all of the headings are GIS friendly (no spaces, no weird symbols, use short titles)
    • Check if your columns are numbers or strings.
      • Sometimes, if it is a string it won’t work right, so you have to go back to your original sheet outside of GIS and change it to number. OR you can add a column in your attribute table
      • Table Options-Add Field, Choose Double and put like 20, 20 in the precision/scale box-right click on the new field-field calculator-set it equal to the column that is reading as a string.
    • Try saving it in many different forms-.xlsx, .xls, .csv, because who knows why GIS messes up sometimes
  • Projecting your shapefile-sometimes you don’t realize that this is what is going wrong so check your projections on your shapefiles when you first add them.
    • When you are pulling data from different sources, sometimes they are projected to different sources
    • make sure the first file you have in your data frame is set to the right projection and coordinate system.
    • If you need to change the projection, do not right click on the layer, you have to go to the ArcToolbox (the red toolbox)-
    • Data Management Tools-Projections and Transformations-Project-put your unprojected shapefile (or incorrectly projected) into the Input Dataset column-in Output Dataset rename your file and save where you are saving everything else- Under Output Coordinate system, choose your projection
    • This will result in a new shapefile with your correct projection
  • Work in the lab
    • Working remotely sounds like a good idea, until you realize that it’s going to take you 5x the time because GIS crashes and you don’t have anyone around you that has any clue what you are doing
    • Other people will be in the lab for a very, very long time doing these midterms so you can use each other! Sometimes when you get stuck, it’s because your brain isn’t working because you’ve been staring at GIS for 30 hours, but someone else may have ideas for you. It speeds up the process enormously!
  • If things keep not working, just start over with that file
    • Cut your losses.
    • Re-download it, sometimes this can save you more time than trying to figure out where you went wrong.
  • GIS is just really frustrating when you are learning it, after the midterm you will definitely be able to troubleshoot A LOT faster because you will have run up against a million things that went wrong in your project and had to fix it


GIS is a super useful skill  that takes time, patience, and mainly patience to master. Keep calm, and map on!

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