The Donabedian ‘st r uct ur e, pr ocess and out com e’ m odel is a useful st ar t ing point for consider ing aspect s of ser v ice deliv er y and ev aluat ion t hat r equir e fur t her at t ent ion.
As far as ‘st r uct ur e’ is concer ned, t his w ould inv olv e m easur es of effect iv eness t hat addr ess a pr ogr am m e’s fr am ew or k and set t ing, such as t he locat ion for t he int er v ent ion, ser v ice and st aff ( Wagner and Guild, 1989) . I n par t icular , issu es of accessibilit y need t o be consider ed in r elat ion t o car er s’ needs; for exam ple, r ur al car er s m ay not find it easy t o access facilit ies pr ovided in lar ge t ow ns or cit ies ( see, for exam ple, Herm an et al. , 1996) .
‘Pr ocess’ evaluat ions aim t o give an under st anding of how a ser v ice oper at es and how it pr oduces w hat it does ( Sm it h and Cant ley , 1985; Ov r et v eit , 1998) . I t is ar gued t hat st udy ing pr ocess can be useful for r eplicat ing ser v ices and finding out w hy som et hing is effect iv e ( Walden and Bax t er , 2001; Ov r et v eit , 1998) , in ot her w or ds, pr ocess ev aluat ion can help t o unpack t he ‘black box ’ ( Pat t on, 1987) by show ing how an int er v ent ion w as deliv er ed.
Wher e int er vent ions ar e incr easingly diver se, em br acing educat ion, suppor t and ot her k inds of psy chosocial int er v ent ions, it is w or t hw hile consider ing feat ur es of ser v ice im plem ent at ion t hat can assist in ident ify ing w hich com ponent s ar e effect iv e. I n addit ion t o under st anding m or e about w hich com ponent s ar e m ost effect ive, t her e is som e agr eem ent t hat know ing ‘how m u ch ’ of t h e
int er v ent ion is r equir ed t o achiev e desir ed out com es ( Zar it and Leit sch, 2001; Bourgeois et al. , 1996) w ould also assist in developing services m ore
Ment al Healt h Pr oblem s
The not ion of pr ocess also em br aces issues of ser v ice ut ilisat ion lev els and t he degr ee t o w hich t he int er vent ion has been deliver ed accor ding t o pr ogr am m e obj ect ives ( Wagner and Guild, 1989) . However, it is im port ant t o bear in m ind t hat j ust k now ing t hat a ser v ice such as a t elephone help- line is available can pr ov ide car er s w it h r eassur ance, r egar dless of t he lev el of use. Clear ly t he r elat ionship bet w een ser v ice use and ov er all effect iv eness needs t o be r econsider ed in t he light of car er needs ( see below ) .
I t has also been ar gued t hat int er v ent ions need t o be:
… described, measured, and monitored to insure that caregivers are receiving [them] as prescribed and to permit replication of treatment effects with similar groups of caregivers.
(Bourgeois et al., 1996: 80)
This ongoing m onit oring of t he im plem ent at ion of int ervent ions has im plicat ions for evaluat ion r esear ch design w her e it is ar gued t hat m easur ing changes in out com es for car er s can occur w it hout confir m ing t hat t r eat m ent goals, such as pr oviding infor m at ion or suppor t , have act ually been achieved ( Zar it and Leit sch, 2001) . Thus, ensur ing t hat pr ogr am m e cont ent s ar e adher ed t o can play an im por t ant r ole in est ablishing over all effect iveness as w ell as ident ifying fact or s t hat m ight affect out com es. Consequent ly it is ar gued t hat
im plem ent at ion st udies, w hile cost ly, can ‘significant ly enhance t he r eplicabilit y, gener alizeabilit y, and int er pr et at ion of fut ur e int er vent ion research’ ( Bourgeois et al. , 1996) .
I n addit ion, it has been ar gued t hat t he r ole of ‘int er v ent ion agent s’ ( facilit at or , say , or t her apist ) should be giv en due at t ent ion in ev aluat ion r esear ch design since t he st y le of pr ogr am m e deliv er y could also be a fact or t hat affect s int er v ent ion out com es ( Bour geois
et al. , 1996) .
How an int er v ent ion is im plem ent ed can consequent ly be seen as a fact or in ach iev in g ef f ect iv eness, and an issue t hat r esear ch designs need t o addr ess. I t is also t he case t hat ongoing m onit or ing of int er v ent ions can play an im por t ant r ole in ensur ing t hat t hey ar e being deliv er ed effect iv ely .
Measuring out com es is a com m on approach in evaluat ion st udies of ser v ices for carers of people wit h m ent al healt h problem s in order t o exam ine t he way in w hich a pr ogr am m e changes client at t it ude, behav iour or k now ledge ( see, for exam ple, Wagner and Guild, 1989) . Thus, m easuring out com es relies on being able t o ident ify cause and effect ( Wagner and Guild, 1989) and is m ost clear ly dem onst r at ed in st udies t hat use cont r ol gr oups, pr e - and post - t est m easur es, experim ent al designs and st andardised m easures of out com e.
St andardised m easures of out com e m ight foc us on m easuring changes in carer bur den, healt h, st r ess or changes in r at es of r elapse et c. ( Higginson, 1994) . Their usefulness lies in t heir validit y and r eliabilit y as st andar dised t est s of behav iour al or at t it ude change, y et t her e ar e also pr oblem s in assum ing t hat such m easur es ar e alw ay s applicable t o t he unique ex per iences of all car er s. Tw o m ain difficult ies are ident ified in t he lit erat ure, nam ely t he problem of using gener ic ver sus specific m easur es and m at ching out com e m easur es t o specific int er v ent ions.
I t has been ar gued t hat w hile gener ic m easur es hav e t he adv ant age t hat t hey can allow for com par ison acr oss differ ent t y pes of car e, t hey should also em br ace specific issues per t aining t o car er s ( Higginson, 1994) and
consequent ly som e hav e ar gued t hat m ore w ork is needed on m easures t hat ar e r elev ant t o car er ex per ience ( Gallagher , 1985) . Ot her s hav e ar gued t hat even specific m easur es, such as car er bur den, m ay be inappr opr iat e in som e cir cum st ances ( Mar t in- Cook
et al., 2000) .
So it is not j ust t hat w e hav e t o use m easur es t hat ar e appr opr iat e t o car er- r elat ed pr oblem s, t hey should also be appr opr iat e t o t he int er vent ion being ev aluat ed. Ther e is a v iew ex pr essed t hat out com es hav e t ended t o be concept ualised in global t er m s – such as a r educt ion in car e - giver burden – w it h lit t le consider at ion as t o w het her or not t he specific int er v ent ion m ight pr oduce t hese r esult s ( Bour geois et al. , 1996; Knight et al. , 1993) .
I f t he ult im at e goal of effect iv eness st udies is t o ‘assess t he out com e or im pact of ser v ices’ ( St . Leger et al. , 1992) w e need t o under st and how t hese out com es can be m easur ed and w hat fact or s m ight cont r ibut e t o t hese out com es bey ond t hose included in t he int er v ent ion.
While t he ‘st r uct ur e, pr ocess, out com e’ m odel is useful for pr oviding us w it h a br oad fr am ew or k w it hin w hich t o locat e som e of t he m ain issues facing bot h r esear cher s and ser v ice dev eloper s, t her e ar e also som e t hem es t hat appear t o be par t icular ly per t inent t o t he st udy of ser v ices for car er s of people w it h m ent al healt h pro blem s t hat w e should also consider : t he im por t ance of t im e hor izons for bot h st udy and design of int er v ent ions; t he r elev ance of needs- based int er v ent ions; and t he im por t ance of m ult iple per spect iv es in st udy and design.