Interest in usability of products has grown over the last 30 years. Product Service System (PSS) designs are geared towards providing products that are not only usable, but also offers a great deal of accessibility, acceptability and satisfaction of service. Usability was originally referred to as “the capability in human functional terms of a product to be used easily and effectively by the range of users, given specific training and user support, to fulfil the specific range of tasks, within the specific range of environmental scenarios. A growing number of companies have transformed their businesses from traditional product manufacturers into product service system (PSS) providers

At Duergo, we triangulate in our assessment. Descriptive studies are often carried out to assess the scope and magnitude of a problem before solutions are suggested. It would help to know users expectations and experience with the PSS and to determine what are the actual challenges and potentials of use, through the conduct of a user trial.

We also encourage an expert evaluation of a PSS by integrating ergonomic principles and involving all stakeholders.  However, good insight on inclusive design will help in designing products/services for present and future challenges. We are proud to say that Duergo limited is one of the pioneering  company offering this expertise in Nigeria.

 Before Use

This is the first stage of data collection. This is carried out after which qualified participants had read through the participant information sheet and signed the consent form. A combination of an interview and questionnaire will be adopted in getting data on anticipated user experience. This will be administered prior to usage by asking participants how they imagine the application of product/services, if they have any prior experience with similar applications and what they would expect from it.

  1. Interview: A semi-structured interview will be conducted for about 5 minute with the use of an audio recorder to get information about relevant user’s profile. A full interview transcript will be documented for future use.
  2. Questionnaire: A paper based five-level Likert scale questionnaire will be administered to participant to get data on user’s expectation on use of product/services.

However, conducting a focus group may also give an idea of anticipated user experience. However this may  be conducted depending on availability of resources and time frame.

During Use

A User trial will be conducted for days and data collected will be via the use of a diary. Participants will be briefed on tasks requiring the use of the product and will be encouraged to use the product/services throughout the stipulated hours as their daily routine demands. This stage helps to collect data on momentary user experience. The diary methods designed is the only way to give access to temporal and longitudinal information gathered in a natural context of the interaction.There are three basic categories of diary protocols which are based on the way in which entries are elicited.

  • Event-contingent protocol: this requires participants to report each time a specific event occurs.
  • Interval-contingent protocol: this involves participants reporting their experience at regular predetermined intervals (for instance, every two hours or every day). Although, this method is widely used, but it does not help participants remember to make diary entries and may lead to missing data.
  • Signal-contingent protocol: This method uses a signaling device to prompt the participants to make an entry. Although, it overcome this drawback of the interval-contingent protocol, but are intrusive.

After Use

After completion of user trial, a debriefing interview and a post-study questionnaire will be administered to get users’ reflection on their experience after usage.

  1. Interview: A semi-structured interview will be conducted for 15 minutes with the use of an audio recorder to get users reflection after usage. It will be more focused on product functionality, perceptions and usage. A full interview transcript will be documented.
  2. Questionnaire: A paper based five-level Likert scale will be administered getting data on users’ experience on product/service. The information designed to be extracted from the questionnaire include:
  • Usefulness of the system
  • Ease of learning system
  • Ease of using system
  • Satisfaction of use
  • Matching expectation to experience of use

The questionnaire will be designed based on findings from  literature reviews.

User Experience ‘UX’  (Min. 3 Months)


Retainership (Min. 1year)

Longer hours of evaluating user experience had proven beneficial to assessing PSS because evaluating a momentary user experience in most cases are not very reliable for predicting user experience in real life. Information about how user’s experience and relationship with a product evolves over time from the early learning and interest to becoming a part of daily life. Furthermore, it is this long term user experience that makes people continue using a product and to recommend it to others. It is known that the salience and relevance of various user experiences changes over time. In addition, user experience is highly dependent on the context of use and user’s internal state of mind.

We are proud to say that Duergo limited is one of the pioneering  company offering this expertise in Nigeria. Please contact us for more details or enquiries.