[Year 12 IT Apps] information needed for gantt charts

[Mark Kelly]

I've always read that slack = float.

Timmer-Arends wrote:
> Since everybody else is having a go....
>  
> "A lead is a forced wait before a task can commence; eg scheduling a 
> Post Implementation Review on a project for two weeks after the 
> installation date. There may be no intervening activity planned, but we 
> have to wait anyway"
>  
> "A lag is a forced wait after an activity before an event can occur; eg 
> you might throw a concrete floor and then have to wait three days for it 
> to cure before laying it with tiles"
>  
> "the slack time for an event is given by subtracting its earliest time 
> from its latest time. This is a measure of the delay which the event 
> could suffer ...and still allow the project to finish within the 
> original estimate range"
>  
> "The float time is the amount of time that a task start could be delayed 
> without affecting the date upon which the succeeding event would occur
>  
> "Managing Information Technology Projects", McLeod and Smith (University 
> of Cape Town), Course Technology, 1996
>  
> ...and then there is the question of how deeply does one have to go into 
> all of this anyway?
>  
>  
> Regards
> Robert T-A
> Brighton SC
>  
> ----- Original Message -----
> 
>     *From:* PARAGREEN, Chris <mailto:Chris.PARAGREEN at kew.vic.edu.au>
>     *To:* Year 12 IT Applications Teachers' Mailing List
>     <mailto:itapps at edulists.com.au>
>     *Sent:* Thursday, March 05, 2009 12:36 PM
>     *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
> 


-- 
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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