Decay

[Peder2911]

A decay transform is based on a time-since transform, where each value decreases according to a half-life function:

0,1,2,3,4

0,1,0.50,0.25,0.125

Is this useful @hhegre? I was asked to do one of these when working as an RA for Håvard N. @ PRIO, but these might not be widely used / useful for modelling?

[hhegre]

We use this all the time in ViEWS. They are more practical than the counts, even when using flexible algorithms such as gams and random forests.

We have to be able to pass the half-life parameter alpha in f(t) = 2ˆ(-t/alpha)

H

On 11 Mar 2021, at 13:20, Peder G. Landsverk @.**@.>> wrote:

A decay transform is based on a time-since transform, where each value decreases according to a half-life function:

0,1,2,3,4

0,1,0.50,0.25,0.125

Is this useful @hhegrehttps://github.com/hhegre? I was asked to do one of these when working as an RA for Håvard N. @ PRIO, but these might not be widely used / useful for modelling?

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHubhttps://github.com/prio-data/views-transformation-library/issues/6, or unsubscribehttps://github.com/notifications/unsubscribe-auth/ACW6H5CLZZGR7NPKEAHQWK3TDCYPHANCNFSM4ZAFQLRA.

Håvard Hegre Dag Hammarskjöld Professor of Peace and Conflict Research, Uppsala University Project director, ViEWS: http://views.pcr.uu.se Box 514, SE 751 20 Uppsala, Sweden Research Professor at Peace Research Institute Oslo Email: @.*** Twitter: @HavardHegre

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[Peder2911]

Absolutely! I implemented this in R in 2020 (seems like ages ago now) as

halflife <- function(t, init = 1){
   function(x){
      init * (0.5 ^ (x * (1/t)))
   }
}

[Peder2911]

Implemented in ViEWS 2 and added in 308cc99a