[Year 12 IT Apps] information needed for gantt charts

[Mark Scott]

In Project Management Lead Time is the time it takes to complete a task or a set of interdependent tasks. The Lead Time of the entire project would be the overall duration of the critical path for the project.

http://en.wikipedia.org/wiki/Lead_time#Lead_time_in_Project_Management


The time required by one task before another task can begin.

Baker, S & K. Baker. On Time/On Budget, Prentice Hall, Englewood Cliffs, NJ, 1992

An overlap between tasks that have a dependency.

Glossary, User's Guide for Microsoft Project 98, Microsoft Corporation, 1997, p307

A technique called lead time is used to represent partial dependencies. By using lead time, certain tasks can overlap by a fixed amount or by a percentage of the predecessor task. For example, testing can start when 30% of coding is finished. It can be thought of as the predecessor task getting a head start, or lead, before the successor task starts. Because the term is easy to confuse with Lag Time, lead time is also referred to as Overlap or Negative Lag.

http://www.leadingproject.com/wiki/Glossary/LeadTime


Occurs when a task should theoretically wait for its predecessor to finish, but can actually start a little early. The time that the tasks overlap is lead time. For example, when replacing computers in a computer lab, you could actually start bringing in the new computers while the old ones were being packed up and moved out. The time during which packing and unpacking can happen at the same time is lead time.

Gospel according to Mark<http://www.mckinnonsc.vic.edu.au/vceit/ganttpert/projmanterms.htm> (Kelly)


Seems to me that the partial dependency theory definition wins the day for Lead time.

Slack and Lag time would seem to be interchangeable for the purposes of Units 3 and 4 ITA.

Mark Scott
Luther College


________________________________
From: itapps-bounces at edulists.com.au [mailto:itapps-bounces at edulists.com.au] On Behalf Of PARAGREEN, Chris
Sent: Thursday, 5 March 2009 12:37 PM
To: Year 12 IT Applications Teachers' Mailing List
Subject: RE: [Year 12 IT Apps] information needed for gantt charts

My first post as a newbie IT teacher!

"Just" a question about some of the definitions for Gantt charts....
According to Potts (p30), lead time is, "... time leading up to or before a task." It further explains the concept, but essentially this is it.
My understanding is that lead time is the time available to begin a dependant task before its predecessor is finished.
For example, you can't set up a computer until the box has arrived, but you can prepare the room in advance.

Similarly, Potts states that slack time and lag time are the same thing, whereas I think they are not.
Slack is the available time to allow for delays, but lag is the time between when a task finishes and when it's dependant task can begin.
For example, if pouring concrete, the actually pouring task might have finished, but you have to wait for the concrete to cure (the lag time) before you can paint it.

Are my definitions too precise for what we need to teach, am I wrong, or am I missing something?

Regards,


Chris Paragreen
IT, Mathematics and Japanese Teacher and Timetabler
Kew High School
1393 Burke Road
Kew East VIC 3102
phone +613 9859 8652 fax +613 9819 7880
chris.paragreen at kew.vic.edu.au<mailto:chris.paragreen at kew.vic.edu.au>
2008 International Year of Languages
Languages Still Matter!

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