A Basic Guide to Using the ExBuilder Analysis Tool

I’m Natalie. Katie showed me how to use the ExBuilder Analysis Tool one time, and I tried to take good notes. My goal in writing the notes was so that I would be able to use the Tool without having to be shown again from scratch how to do it. That’s my disclaimer that these notes might not be detailed enough if you have never used the Tool before. I’ve tried to expand upon a few things, so you can go ahead and try it out, but I just wanted to get the disclaimer out of the way. My other disclaimer is that I don’t do anything incredibly fancy in here. The take-home message is that, while these notes might help you, it is entirely possible, probable even, that you will need to get help using the Tool at some point, whether it’s for fancy stuff or really basic stuff. My final disclaimer is that there is no doubt more than one way to do certain things, and this is just a guide for one of those ways. Be your own person and all that.

Data Conversion
I am assuming that you set up your experiment to include the relevant messages for your analyses. For example, you might have a special message sent to the data file every time a new picture goes on the screen, or every time a subject clicks on something. This guide assumes you are happy with the messages in your data files.

Opening the Analysis Tool
Go ahead and open ExAnalysis. It might crash, look warped on the screen for a while, or just take a long time to open. You might have to try opening it again. But once it is open, you will see along the left side that there are many, many data bases loaded. This represents the productivity of your colleagues, and it should make you feel a little bit bad about yourself. That is normal. Be kind, though, and do NOT unload anyone’s database. This is bad. Try your best to ignore the databases of others. Yes, a loaded data base means loaded for all users on that computer. The data base files, .ldf and .mdf, are big and go together, and at last check there was no easy way to transfer them to another computer.

Create New Database
Click on Analysis Databases in the sidebar to get the correct option boxes on the lower left. When it appears, click on Create New Database. You have to click on Experiment Settings, open Settings window, and ADD the script from your experiment. PortName must be in your script for the Analysis Tool to work properly, but don’t ask me exactly what that means.

Q&A
Now the Tool will ask you several questions about your data files. I am not a guru, in the sense that I don’t understand the deeper meaning of many of these questions. That might be nice info for the wiki, but as a non-guru, I’ll try to give practical answers, but you might want to consult an expert or play around with these parameters at some point.

Errors
Now is the time you might see error messages appear. Those can range from trivial to breathtakingly serious. I can’t help you much with errors, but most of us have dealt with some variety of error in the past, so you’re in good company. In order to proceed, though, I am going to assume that nothing bad happened during importation.

Data Filters
Ultimately what you probably want from the Tool is eye-tracking data aligned to certain stimulus onsets. Am I right? We’re almost there. In the left bar, where you see your database listed, click on the Filtered Data bracket, and click New Filter. Here is another point at which I can’t completely help you. I don’t know what you did and I don’t know what you’re interested in. But here is where you can play around and filter data by conditions. You have to remember what you called things in your script, and it might be helpful to open the script so you can look at it. But, as an example, you might want to type r_cond==”generic” in the box, and that would give you data from the “generic” condition in your study. Always click SAVE. You have to write new filters from scratch to avoid overwriting old filters, by the way, so be careful.

IMPORTANT NOTE: If you track both eyes, Exbuilder WILL NOT copy the data from the better eye over the data from the worse eye, and some of your subjects might have a better track from the left eye and some a better track from the right eye. You can't select the best eye for all participants if you track both eyes, unless you do something special to fix this problem on your own. It can't be done automatically in Exbuilder, which is why I only track the better eye to begin with, unless both are "GOOD" according to the eyelink. If you lock out any eye that is not "GOOD" when you are running the study, Exbuilder will copy the data from the good eye to any one that wasn't tracked. So, you can track the right eye of subject 1 and the left eye of subject 2, etc, and then analyze LP_tag or RP_tag -- as long as you don't track an eye that isn't "GOOD" you will always have data that is pretty good. If you have personal reasons for not wanting to just track one eye, or you already did the study and you tracked both eyes, then you will have to write a script to edit the asc files if you want to make sure you get the best data from each file. -Katie

That’s about it! I can’t help you with much more than this. Again, you might want to watch someone do it once and then use these notes as a reminder. Or you might need someone else to explain ad nauseam the details and minutiae. Chances are you probably know who the most detail-oriented people in the lab are, and you can ask them if you have specific questions. All mistakes here are mine, but Katie should get the credit for showing me how to use the Tool. If you have anything to add to this tutorial, feel free!

Analysis Advice Column

Okay this section is not edited yet, but it's part of a correspondence between Katie and myself that some people might find important. Details later, I hope, but it pertains to formatting data for subject/item ANOVA:

Dear Katie

Dear Natalie, know exactly what you mean dude. The data shown in the look count window is always averaged by subjects and items together so it is totally impossible to officially analyze it, since you can't get the averages for the individual subjects, and also you can't add subject or item as a random effect to any regression model. It is poorly designed.

I have dealt with this before though, when I was doing an ANOVA on 4 pic data. You have to export the data by subject, which is not that hard. But, I'm not sure how I aligned the data when I did this. I think if you line it up with the noun onset selected in the look count window and THEN export the data from that window, by subject, that will work. After you export the data it should be saved in different .csv files with the subject names in the files. You should be able to tell by looking at the exported files if they are aligned or not because if they are, then the initial values in the time column will be negative, otherwise they will start at 0.

Then annoying thing is that you have to do this separately for each condition. So for example, in my experiment it was 2x2, so there were 4 different "conditions" (so 4 filters) and I had to export the data separately by subject for each one. So then there were 4 files for each subject. Also, for each subject in each condition I wanted the averages for different segments (0-200ms, 200-400, 400-600 are what I used). It sounds like this is what you want to do, too.

So after you export the files then you can calculate the averages for each subject for each condition for each time segment, for the ANOVA. But you have to put it into excel and then do some things to it to get the averages -- exbuilder doesn't average anything on it's own. I know I had some macros that I used to do some of it, but it's hard to describe exactly what I did over email. In the end, after you get the averages you can copy and paste them all into one file, and then that will be what you use for the analysis. If you want we can meet in person and I can try to show you what I did. That might be more helpful than this email. I don't know.

It's kind of hard to believe what we have to go through to use the stupid analysis tools. But anyway, there IS a way to do it, it just isn't as easy as it should be unfortunately...

Katie

SQL Database Information
One further thing you might want to do once you have done some basic manipulations in ExAnal is to create a database that preserves subject and item info. The cut-and-paste method described above will give you pretty graphs that are representative of pooled data. This will NOT necessarily match the by-subjects or by-items averages you really wish to compare. You will notice, possibly with alarm, that there IS NO subject OR item information in your data file after performing the steps above. The previous section made some mention of this, but now I am offering you a real solution based on some wisdom that has trickled down my way.

There are, in fact, TWO solutions. The first one is to export each subject's data file individually from ExAnal. To do this you will

This will generate you a separate .csv file for EACH subject (or item). Then you must concatenate by hand after inserting an additional column of data to indicate the subject name or item number. I cannot offer many details about this method, since I do not really do things this way.

THE SQL SOLUTION
Another thing you can do to capture all the information you could possibly want into one file is to use SQL databases. It is a little quirky but I will relay the wisdom as I have learned it in the following easy steps:

Hope this helps! Now you should have one big data file that has subj and item info preserved, is comma-separated, and has the columns you selected in the filtered data portion of ExAnal. Now you can go forward with your analysis.

NOTE: As of October 2015, probably due to an SQL Server update, the following characters and words should not be used as (parts of) filter names:

  1. hyphen

TanenhausLab: ExBuilderAnalysisTool (last edited 2015-10-26 15:10:15 by AnnePierSalverda)

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