"Celeration line method" is another form of naming "Split-middle method".
See the following pages in English for the meaning and methods applied.

http://www.thefreelibrary.com/Interrater reliability of ther...
The split-middle method of trend estimation, also referred to as the celeration line method is...
The most widely advocated supplement to visual analysis is the split-middle method of trend estimation, originally described by White [20] and presented by White and Haring.
When a series of measurements of a process is treated as a time series, trend estimation is the application of statistical techniques to make and justify statements about trends in the data.

http://www.thefreelibrary.com/Interrater reliability of ther...
. [21] The split-middle method of trend estimation, also referred to as the celeration line approach, is an easy-to-compute way to develop a trend line for graphed data. The procedure involves fitting a trend line through the median values of each half of the baseline data. This line is projected into the treatment phase and allows comparison of the obtained results with the predicted trend (Fig. 1). The assumption is made that if the intervention had no impact, then the proportion of data points above and below the trend line would remain essentially the same across both phases of the design. The computation steps and interpretation of the split-middle method of trend estimation have been widely reported in the literature
Median value - the value below which 50% of the cases fall

The same method described, Spanish.

http://www.unesco.org.uy/red-m/glosariom.htm
El método de la mediana permite trabajar con atributos cualitativos con los .....

http://www.cemla.org/pdf/v_red_grippa.PDF
Métodos estadísticos ..... la variación del indicador calculado con el método de la mediana es inferior a la ...

http://www.doyma.es/cardio/ctl_servlet?_f=40&ident=13140540
... de pacientes asintomáticos por el método de la mediana

http://ciberconta.unizar.es/LECCION/cluster/100.HTM
En el método de la mediana el nuevo centroide es la media de los centroides de los ... Dado que la mayor parte de los paquetes estadísticos proporciona las ...

Obviously it is not a regression.