By PaulaBlu - 7/3/2017
Dear Inquisit team/ Dave,
We are currently running an online experiment with the Inquisit Web tool.
Our data file has a size of 17.4MB (there are a lot of pictures included which we definitely need in an accepatable quality) and our script is quite long with 18236 lines in total.
When running the experiment with the local data file, loading time is under 2 seconds, however, in the online version the loading time is between 3-5 minutes. This naturally lowers the motivation of our potential participants quit a lot to participate in our investigation. We were thinking about using a different server, if that's the problem, but we aren't sure right now. We are thus wondering whether a) you have an idea why loading the experiment takes so long and b) whether you have any suggestions on how to reduce the loading time (apart from reducing the file size or the scope of the script)
We'd be very grateful for some advice
Yours
Paula
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By Dave - 7/4/2017
+xDear Inquisit team/ Dave, We are currently running an online experiment with the Inquisit Web tool. Our data file has a size of 17.4MB (there are a lot of pictures included which we definitely need in an accepatable quality) and our script is quite long with 18236 lines in total. When running the experiment with the local data file, loading time is under 2 seconds, however, in the online version the loading time is between 3-5 minutes. This naturally lowers the motivation of our potential participants quit a lot to participate in our investigation. We were thinking about using a different server, if that's the problem, but we aren't sure right now. We are thus wondering whether a) you have an idea why loading the experiment takes so long and b) whether you have any suggestions on how to reduce the loading time (apart from reducing the file size or the scope of the script) We'd be very grateful for some advice Yours Paula
Loading time is definitely affected not only by the overall size, but also by the total number of files involved. Meaning: Downloading 200 files at 100KB each will take longer than downloading 20 files at 1000KB each, although the overall size is ~20MB in both cases. Reducing file size should improve things a little bit (e.g. use a compressed image format such as JPG instead of uncompressed BMP files), but the performance hit related to the total number of files involved will remain, especially under Inquisit 4 Web.
If you do have Inquisit 5 Web at your disposal, using that version would be an option. The most recent version of Inquisit 5 Web has introduced some changes that should improve download performance in cases where many files are involved and the resulting download time should be noticeably faster compared to Inquisit 4 Web (although the performance hit will not go away completely).
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By PaulaBlu - 7/4/2017
+x+xDear Inquisit team/ Dave, We are currently running an online experiment with the Inquisit Web tool. Our data file has a size of 17.4MB (there are a lot of pictures included which we definitely need in an accepatable quality) and our script is quite long with 18236 lines in total. When running the experiment with the local data file, loading time is under 2 seconds, however, in the online version the loading time is between 3-5 minutes. This naturally lowers the motivation of our potential participants quit a lot to participate in our investigation. We were thinking about using a different server, if that's the problem, but we aren't sure right now. We are thus wondering whether a) you have an idea why loading the experiment takes so long and b) whether you have any suggestions on how to reduce the loading time (apart from reducing the file size or the scope of the script) We'd be very grateful for some advice Yours Paula Loading time is definitely affected not only by the overall size, but also by the total number of files involved. Meaning: Downloading 200 files at 100KB each will take longer than downloading 20 files at 1000KB each, although the overall size is ~20MB in both cases. Reducing file size should improve things a little bit (e.g. use a compressed image format such as JPG instead of uncompressed BMP files), but the performance hit related to the total number of files involved will remain, especially under Inquisit 4 Web. If you do have Inquisit 5 Web at your disposal, using that version would be an option. The most recent version of Inquisit 5 Web has introduced some changes that should improve download performance in cases where many files are involved and the resulting download time should be noticeably faster compared to Inquisit 4 Web (although the performance hit will not go away completely).
Hi Dave,
So does that mean that the problem exists entirely due to file size/the number of files and that the length of the script and the speed of the server has no influence on the loading time?
We tested the download speeds on several computers, and according to that the experiment should be loaded within a few seconds. So where is the bottleneck?
Yours
Paula
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By seandr - 7/5/2017
Hi Paula,
File size definitely counts. If you use a compressed format for the images such as JPG or PNG, you should see a notable drop in download times.
There is an additional cost with Inquisit 4 related to the number of files, as Dave notes. We've optimized this cost away in version 5. But you will still see shorter load times by using more efficient file formats for your image.
-Sean
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