[Year 12 IT Apps] information needed for gantt charts

Mark Kelly kel at mckinnonsc.vic.edu.au
Thu Mar 5 13:52:13 EST 2009


Hmmm.  I have trouble with that first definition by Wikipedia.  I've 
never heard of lead time defined like that before.

Mark Scott wrote:
>  
> 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! *
> 


-- 
Mark Kelly
Manager - Information Systems
McKinnon Secondary College
McKinnon Rd McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085
School Phone +613 8520 9000
School Fax +613 9578 9253
kel at mckinnonsc.vic.edu.au

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