A group decision system is being built over a network and, because of the lag in

Question

A group decision system is being built over a network and, because of the lag inherent to the network, is experiencing delays. For each of the situations below, suggest the longest acceptable amount of time the delay could last without negatively affecting the user. Provide a rationale for each estimate, and include relevant examples and research in your response in 1- 2pages

1.System confirming the user’s password during log-in

2.Synchronous group editing of a document

3.Asynchronous critiquing of other participants’ work

4. Voting on serious issues

Explanation / Answer

Before providing answers to the queries, it will be good to understand few concepts.

a) Response time: Response time is defined as the number of seconds taken between from the moment users initiate an action and the moment computer provides its response. After getting computer's response, users begin thinking for the next action.

b) User think time: It is the number of seconds taken by the user in thinking about his/her next action.

c) User planning time: Time taken by the user in planning for next action/task, while comupter is busy in formulating and generating is response.

Most of the time users expect a prompt response and delay beyond a quantum of milliseconds annoy them. But for networked resourses, they expect and accept a certain delay. However, it can be understood the computer's response time should be well within the limits of user's planning time. It is observed that shorter response times (< 1 second) increase productivity, but too much fast response can also lead to increased error rates. Hence, it becomes necessary to identify an optimal value of response time depending on the type of task, characteristics of the user etc. Slight variation (+/- of 50% of mean time) in resonse time is acceptable. Unusual delays (approximately twice of anticipated time for an activity) affect the user negatively. How long a user will wait for computer's response depends on his/her expactation for a particular task from past experiences.

Answers:

1. A slight delay of about 0.2 or 0.3 seconds possibly after entering the password on log-in page is permissible. This time will be comsumed in checking the user's creadentials. Beyond this, it may affect the user because he assumes a quick confirmation of login or response in case of password mismatch.

2. For an activity like synchrounous editing of a document by a group, it is necessary that changes being made by different users of the group are displayed to all users instantly (within less than 100 ms). For this, display rate of screen should be sufficient enough to fill the text instantly. However, it can be comspromised by the issues of network bandwidth, server performance etc. An unwanted delay in showing all the changes by different users may lead to a chaotic/corrupt document. To avoid this, provision of version control recording all changes to the document will be required so that in case of a failure, proper version of document should be retrieved.

3. For this type of work, it is not required to ensure instant (without any perceived delay) availability of data. A person can critique other persons' work as and when it is submitted to him/her. He/she will be able to finish the work at his/her own pace, although within the specified timeframe. In case work is not available to him/her, he/she can wait (for a few seconds) till it is made available.

4. For a voting kind of task involving recording of a person's opinion on a number of issues, he/she can wait for a certain amout of delay (e.g. 6-8 seconds), while recording his/her vote and getting the confirmation whether vote is recorded successfully.

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