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  • SOWA description
    Sowa - Subjective Overall Workload Assessment Sowa is a Subjective Overall Workload Assessment method and supporting software.

    The subjective workload evaluation includes four fundamental dimensions: (1) Manual material handling, (2) Material work environment, (3) Body posture and movement, (4) Mental demand. Each of these dimensions is characterized by several attributes. The detailed structure is presented in table below Workload dimensions and properties.

    The person being examined is asked to rate each of the specified workload dimensions parameters on the 20 step bipolar scale#Questionnairs.

    In order to determine weights for individual workload attributes, the Analytic Hierarchy Process (AHP) technique developed by Saaty (1977, 1980) was used.

    Subjects first make pairwise comparisons of parameters within the confines of each dimension and then the same procedure is used for calculating weights for the workload areas. Products of these weights and obtained earlier parameters scores are summed up in every dimension. These values are then multiplied by dimensions weights. The sum of the four weighted numbers gives the overall perceived workload assessment index (OPWAI).

    Taking advantage of the AHP technique for determining the importance hierarchy of workload components, allows for calculating the consistency ratio (CR) for every dimension. It is assumed that a CR value less than 0.1 indicates a high comparisons consistency, whereas CR values equalled approximately 0.5 signify considerable incoherence.

  • Workload assessment procedure
    Workload parameters evaluation
    Workload parameters pairwise comparisons
    Workload dimensions pairwise comparisons

  • Features of the SOWA software
    Takes into into account physical activity outside work
    Specifies relative importances of work dimensions
    Computes consistency of the obtained results
    Allows for comprehensive pain ailments evaluation
    Automatically generates and prints out questionnaires
    Exports the results to Microsoft Excel

Diagram of utilizing SOWA software for workload, pain, and physical activity assessment
Questionnaires generation and print out
Filling out questionnaires by subjects
Entering data into sowa software
Examination results presentation and analysis
Possible export of selected results to ms excel

Workload dimensions and attributes
1. Manual material handling (MMH)
1.1. Weight of load
1.2. Frequency of load
1.3. Duration of load
1.4. Moving distance of load
2. Material work environment (MWE)
2.1. Microclimate (temperature, humidity)
2.2. Lighting (light intensity, glares)
2.3. Noise
2.4. Vibrations
2.5. Direct exposure to chemicals
3. Body posture and movement (BPM)
3.1. Standing
3.2. Stooping
3.3. Squatting, kneeling
3.4. Twisting
4. Mental demand (MDE)
4.1. Time load
4.2. Mental effort load (counting, remembering)
4.3. Psychological stress load
Questionnaires for assessing the workload
Workload parameter comparisons
Workload parameter comparisons
Workload parameter evaluation
Workload parameter evaluation

Main window of SOWA software
Main window of SOWA software by Rafal Michalski
Perceived workload assessment results presentation
Perceived workload assessment results presentation in Sowa software by Rafal Michalski
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