[Gretl-users] Least squares/linear regression examples?

Hello Great Minds: Long time listener, first time caller. We currently use gretl for our in-house manufacturing system in various capacity. When I say gretl, I mean a command line Linux version that we interface with using PHP, data points stored in MySQL. We now have a new calculation for Gretl, but unfortunately the guy who handled all of this work has moved on. I am trying to work out a solution to the new problem, which is undoubtedly quite simple to those wiser than myself. We have a set of data points (happen to be hours on different job numbers). When these points are graphed and the trend line applied, it's clear whether the times are increasing or decreasing. We now want to quantify this as part of an ongoing review of time submitted to the system, so that we can determine for X amount of current jobs, whether overall time is increasing or decreasing, and maybe by how much. I have a rudimentary statistical education, so I've been doing some research and a linear regression seems the best option for us. Ideally what we are doing is supply a set of data points to gretly and having it provide us with some approximation of what is happening-the trend-in the points. Please bear with me, as I have to both come to terms with the statistical functions required AND how to handle this using gretl, which I think is our best option since we already have it integrated. I was also thinking that maybe if there was a way to derive from the trend line the slope, that might be exactly what we are looking for? A slope should identify whether the times are increasing or decreasing and by how much. So can you guys provide me any reference pages on using gretl in this fashion? Preferably over command line, which I can translate to PHP usage. Any kind of GUI/Windows use is out, unless there is a clear understanding of how to translate to the command line environment. Also, if my understanding of what needs to happen is any way incorrect, feel free to correct me and set me straight Thanks in advance for any help you can offer. -- Ryan .