Forum Reader Wrote:
-------------------------------------------------------
> Anonymous Wrote:
> > FR-
> > Sorry I never did get back to you. Use the raw
> > data here:
> >
http://www.fcps.edu/Reporting/
> >
> > Go by cohorts and adjust starting with an
> > adjustment using the 5 year average of inflows
> or
> > outflows. This is the standard FCPS model for
> > projections. Once you understand the model
> FCPS
> > uses and backtest for errors you can see the
> > problems and adjust. ...
> >
> > Since you are adept with the CIP go back say 2
> > years and see where schools were projected to
> be
> > today and where they actually are now.
> McKibben
> > recommends a 2% per year error variance.
>
> So many posts this morning! I'll try to respond to
> a dozen or so.
>
> It is easy to look at this year's first graders
> and estimate how many second graders a school will
> have next year. To guess third graders is a little
> trickier because some students will move to GT
> Centers.
>
> The next three years are also fairly easy to
> predict (3rd to 4th to 5th to 6th). Estimating the
> numbers into a middle school is much more
> difficult because so many elementary schools are
> split into other pyramids and because so many
> students move into or out of GT Centers or private
> and parochial schools.
>
> The estimate from seventh to eighth is again
> easy.
>
> The estimate from eighth to ninth is the hardest
> of all. Many middle schools are split between
> high schools. Some students will "come back" to a
> pyramid from a GT Center. Some will leave for
> Jefferson. Some will go to or come back from
> private and parochial schools. Some will pupil
> place for various reasons.
>
> After ninth grade different high schools show
> significant differences in loss rate. Jefferson
> has very few losses (no surprise).
>
> The below numbers show the FOUR year decrease in a
> particular grade (e.g., “Class of 2007”) from
> September of their freshman year to June of their
> senior year for the last four years. All data are
> from the “Membership” numbers posted on the FCPS
> website to which you so kindly pointed us.
>
> There are many reasons behind these numbers and
> leaving before graduation is not necessarily
> “bad.” However, some may find it significant that,
> for whatever reason, about eighteen percent of
> Herndon and South Lakes freshmen probably won’t be
> there to graduate, while at the other high schools
> in the current boundary discussion that number is
> closer to five percent.
>
> It should also be noted that in the Class of 2007
> the loss rate at Oakton and South Lakes were
> almost the same, Chantilly was very low, and
> Herndon very high. I am not trying to explain
> these numbers, only to state them.
>
> Chantilly
> Class of 2007 0.31%
> Class of 2006 4.79%
> Class of 2005 5.01%
> Class of 2004 10.83%
> Average 5.05%
>
> Herndon
> Class of 2007 22.50%
> Class of 2006 17.31%
> Class of 2005 18.83%
> Class of 2004 14.11%
> Average 18.19%
>
> Langley
> Class of 2007 5.83%
> Class of 2006 6.09%
> Class of 2005 1.71%
> Class of 2004 3.42%
> Average 4.26%
>
> Madison
> Class of 2007 3.71%
> Class of 2006 5.37%
> Class of 2005 9.52%
> Class of 2004 6.63%
> Average 6.24%
>
> Oakton
> Class of 2007 11.71%
> Class of 2006 4.23%
> Class of 2005 3.82%
> Class of 2004 -2.29%
> Average 4.62%
>
> South Lakes
> Class of 2007 11.75%
> Class of 2006 18.70%
> Class of 2005 18.72%
> Class of 2004 19.71%
> Average 17.36%
>
> Westfield
> Class of 2007 4.77%
> Class of 2006 6.57%
> Class of 2005 6.75%
> Class of 2004 6.42%
> Average 6.11%
I don't recall making a value judgment...I just showed you how to do your own projections. I am focused on the high school level which you astutuely show is the hardest to predict (although some would say kindergarten is the hardest). FCPS averages the actual inflow/outflow actual numbers between cohorts. So how many kids do we lose between 5th and 6th grade over the last 5 years. That is what is added or subtracted along with any expected development in projecting next years 6th grade class.
Have you looked at the CIP from 2 years ago to check projected vs. actual for this year?
How do you measure students that come or leave for more subjective reasons or for macroeconomic reasons?