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Goal of the study was to compare the performance of ‘Planning Line’ glyphs (PL) with PERT charts.
The reason for the decision to compare PL with PERT lies in the ability of PERT to display uncertainties, related to the ending, beginning and duration of a certain project task. Exactly this ability is one of the main advantages, the ‘Planning Lines’ graph provides. The reason for not using similar graphs, like the GANT graph, is that they are not able to display uncertainties in time. Following this the comparison with PL would not be very expressive.

1. Subjects

The subjects are graduate students of informatics and business informatics in a usability engineering workshop.
The Austrian university system allows students to organize their studies in a very individual way. This enables them to determine their own schedule and to work part-time during their studies. Therefore the subjects participating in this workshop exhibit rather heterogeneous knowledge and experience levels.
We provided a tutorial, that briefly repeated how to use PERT, a method known by most participants, and introduced the new method ‘Planning Lines’, to guarantee the minimal common level of knowledge for the experiment.

2. Number of Subjects

In December 2004, 48 students of the workshop ‘Usability Engineering’ participated in the experiment.
From the experiment preparation team four members supervised the experiment and answered questions concerning the experiment or questionnaire.

3. Experiment Objects and Procedures

This section provides a short overview of the experiment objects, which were used in our study.
The experiment participants received the following experiment materials

• 1. Background Questionnaires: A one-sided questionnaire was provided at the beginning of the experiment. Participants were asked to give general information (Name, Age…) and specific information about their experience with PERT and similar graphs.
• 2. Answering sheets for task solutions
  • a. Part A: This part contained a three sided answering sheet for questions and tasks, concerning the usage of PL or PERT. Four different versions of this part were available, differing in treatment (PL, PERT) and data set (1, 2), and were randomly handed out to the subjects.
  • b. Part B: This part contained a project plan and a five sided answering sheet for questions, which were based specific tasks in the project plan. Four different versions of this part were available, differing in treatment (PL, PERT) and data set (1, 2), and were randomly handed out to the subjects.
  • c. Part C: On an on-sided answering sheet participants had to draw a graph, based on textual task information. Once again four versions were available, differing in treatment (PL, PERT) and data set (1, 2), and were randomly handed out to the subjects.
• 3. Feedback Questionnaire: At the end of the experiment every subject had the possibility to give his or her feedback to the PL graph.
  Before handing out the experiment material, in the order listed above, a short tutorial, that briefly repeated how to use PERT, a method known by most participants, and introduced the new method ‘Planning Lines’, to guarantee the minimal common level of knowledge for the experiment, was held by one of the experiment design members.
  Afterwards the experiment material was handed out. There was a time limit of 45 minutes to finish the given questionnaires and answering sheets. Additional to this subjects were asked to note down the current time before start and after finishing a part of the answering sheet. This was done to measure the time every participant needed to solve the given questions and tasks (in some hypotheses we refer to the time a subject needs to finish a task).

Finally subjects had the possibility to give feedback to the PL graph in a one-sided questionnaire.