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Towards a Taxonomy of Common Factors inPsychotherapyResults of
an Expert Survey
Wolfgang Tschacher,* Ulrich Martin Junghan and Mario
PfammatterDepartment of Psychotherapy, University Hospital of
Psychiatry, University of Bern, Bern Switzerland
Background: How change comes about is hotly debated in
psychotherapy research. One camp considersnon-specic or common
factors, shared by different therapy approaches, as essential,
whereasresearchers of the other camp consider specic techniques as
the essential ingredients of change. Thiscontroversy, however,
suffers from unclear terminology and logical inconsistencies. The
TaxonomyProject therefore aims at contributing to the denition and
conceptualization of common factors ofpsychotherapy by analyzing
their differential associations to standard techniques.Methods: A
review identied 22 common factors discussed in psychotherapy
research literature. Weconducted a survey, in which 68
psychotherapy experts assessed how common factors are implementedby
specic techniques. Using hierarchical linear models, we predicted
each common factor by tech-niques and by experts age, gender and
allegiance to a therapy orientation.Results: Common factors
differed largely in their relevance for technique implementation.
Patientengagement, Affective experiencing and Therapeutic alliance
were judged most relevant. Commonfactors also differed with respect
to how well they could be explained by the set of techniques.
Wepresent detailed proles of all common factors by the (positively
or negatively) associated techniques.There were indications of a
biased taxonomy not covering the embodiment of
psychotherapy(expressed by body-centred techniques such as
progressive muscle relaxation, biofeedback trainingand hypnosis).
Likewise, common factors did not adequately represent effective
psychodynamic andsystemic techniques.Conclusion: This taxonomic
endeavour is a step towards a clarication of important core
constructs ofpsychotherapy. Copyright 2012 John Wiley & Sons,
Ltd.
Key Practitioner Message: This article relates standard
techniques of psychotherapy (well known to practising therapists)
to the
change factors/change mechanisms discussed in psychotherapy
theory. It gives a short review of the current debate on the
mechanisms by which psychotherapy works. We provide detailed proles
of change mechanisms and how they may be generated by practice
techniques.
Keywords: Common Factors, Psychotherapy Techniques, Therapy
Process, Change Mechanism, Theory ofPsychotherapy
INTRODUCTION
Psychotherapy research has settled the question of theefcacy of
psychotherapy to the positive since several years.Numerous studies
and meta-analyses have demonstratedthat psychotherapy works for
most forms of psychopath-ology. The eld has arrived at a consensus
that psycho-therapy is more effective than no treatment and
thanplacebo controls (Lambert & Ogles, 2004). Yet sources
of considerable disagreement remain: they concern therelative
efcacy of different psychotherapy approachesas well as,
importantly, the mechanisms bywhich psycho-therapy becomes
effective. In this context, major contro-versies have addressed the
Dodo-bird verdict (i.e. allpsychotherapy approaches have similar
benets; hence,all must have prizes) and the role of common
versusspecic factors of psychotherapeutic change (Wampold,2001;
Beutler, 2002; Chambless, 2002; Luborsky et al.,2003). This
controversy has split the eld into two oppos-ing camps: one camp
attributes therapeutic change tospecic ingredients and factors
(DeRubeis et al., 2005),and the other favours a common-factor model
(Wampoldet al., 2001).
*Correspondence to: Prof. Dr. Wolfgang Tschacher, Department
ofPsychotherapy, University Hospital of Psychiatry, University of
Bern,Laupenstrasse 49, 3010 Bern, Switzerland.E-mail:
[email protected]
Clinical Psychology and PsychotherapyClin. Psychol. Psychother.
21, 8296 (2014)Published online 6 November 2012 in Wiley Online
Library (wileyonlinelibrary.com). DOI: 10.1002/cpp.1822
Copyright 2012 John Wiley & Sons, Ltd.
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The specic-ingredients camp focuses on techniques asthe causal
agents of therapeutic change. In recent years,specic ingredients
have become the basis of practiceguidelines and of empirically
supported therapies inevidence-based medicine (Chambless &
Ollendick, 2001).The opposing camp emphasizes that core
therapeuticfactors shared by different approaches account formost
of the benets achieved in psychotherapy. Thesefactors of
therapeutic change are called non-specic orcommon and thus may
explain the Dodo-bird verdict.Common factors are not theoretically
anchored in the
treatment models of the different schools of psychother-apy, nor
are they considered in the treatment models forspecic mental
disorders. The concept can be traced backto Saul Rosenzweigs (1936)
implicit factors shared bydifferent methods of psychotherapy, such
as the relation-ship between patient and therapist. In the 1960s,
JeromeFrank (1971) developed his Common Component Modeladvocating
four common factors: a conding relationship;a socially sanctioned
institutional context; a therapeuticrationale (myth) offering an
explanation of a patientsproblems; and particular tasks and
procedures to solvethese problems (rituals). Subsequently, a series
of authorshave proposed further sets of common factors, such
asaffective experiencing, cognitive mastery and
behaviouralregulation (Karasu, 1986); problem confrontation,
correctiveemotional experience (Weinberger, 1995); resource
activa-tion, clarication and coping (Grawe, 1995).The controversy
between specic and common factors
(. . .) has pervaded several decades and is still the
guidinginuence that directs the reections in the eld aboutfactors
responsible for change (Castonguay & Beutler,2006, p. 632). It
is becoming increasingly evident, how-ever, that this horse race of
determining the mostrelevant change principle assumes a dichotomy
of spe-cic and common factors that is based on terminologicaland
conceptual inconsistencies, has little empirical valid-ity and
fails to do justice to the complexity of the thera-peutic change
process.Especially how the term common factor is currently
being used is confusing (Lampropoulos, 2000): the
literatureshows great inconsistency as to which levels of the
GenericModel of Psychotherapy (Orlinsky et al., 2004) commonfactors
refer to. Specic factors, however, solely refer tothe technical
aspect of the therapeutic process, i.e. theyare identical to
psychotherapeutic techniques. In otherwords, common and specic
factors address differentaspects and levels of the
psychotherapeutic process(Pfammatter & Tschacher, 2012). It is
therefore inadequateto contrast common factors with specic factors
becausethese concepts reside at incommensurate logical
levels.Rather than competing in a horse race against eachother,
specic factors, i.e. techniques, and commonfactors should be viewed
by their interaction (Karasu,1986; Goldfried, 1980; Butler &
Strupp, 1986).
In addition, a dichotomy of common versus specicfactors has not
received empirical support. For both,signicant relations to outcome
have been shown: A seriesof meta-analyses demonstrated that several
aspects of thecommon factor therapeutic alliance, such as empathy
orgoal consensus, are clearly related to positive outcome(Lambert
& Cattani, 2012; Norcross & Wampold, 2011a).At the same
time, also techniques such as exposure,empty-chair technique,
paradoxical intention and particu-lar forms of interpretations were
(. . .) found to be consist-ently and strongly associated with
positive therapeuticoutcome (Orlinsky et al., 2004, p. 341). Thus,
the questionis less which of both, techniques or common factors,
aremore important but how each relate to the other so thatthey can
be successfully tailored to a specic patient(Norcross &
Wampold, 2011b).Clear terminology and accurate conception of
process
variables is of paramount importance in this context.
Cur-rently, several projects aim at creating a common languagefor
techniques, such as the development of a Comprehen-sive
Psychotherapeutic Interventions Rating Scale byTrijsburg et al.
(2002), the Multitheoretical List of Thera-peutic Interventions by
McCarthy and Barber (2008) andthe web-based project Common Language
for Psychother-apy byMarks (2010). The Taxonomy Project presented
hereis an attempt to empirically arrive at a more preciselanguage
for, and conception of, common factors in psycho-therapy. The
Taxonomy Project deviates from the either-ormentality prominent in
the camp of school-specic anddisorder-specic factors (medical
model) and the campof the proponents of common factors (contextual
model;Wampold et al., 2001). Rather than mutually exclusivecauses
of change, we consider specic techniques and com-mon factors as
associated components of psychotherapyprocess.For the present
study, we decided to analyze the
relationships between specic techniques and commonfactors
through the use of expert opinion. We collectedassessments of
psychotherapy experts in the frameworkof an extensive survey, to
which researchers of psycho-therapy were invited. Techniques were
treated as givenanchor points (i.e. as independent variables)
because tech-niques are operationalized and dened in the manualsand
textbooks of different psychotherapy schools. In otherwords, we
used techniques as the entities that allowdescribing the dependent
variables in our study: thecommon factors of psychotherapy. Doing
this, the goalof the Taxonomy Project was to contribute to a
clearerdenition and conception of common factors. Thereby, wealso
wished to introduce a novel understanding of speci-city in the
common versus specic debate: common factorsmay be considered specic
insofar as they may be gener-ated by specic subsets of techniques
and possibly inhibitedby other subsets of techniques. We
hypothesized thatcommon factors would markedly differ with respect
to
83Taxonomy of Common Factors in Psychotherapy
Copyright 2012 John Wiley & Sons, Ltd. Clin. Psychol.
Psychother. 21, 8296 (2014)
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their relations to specic techniques. This would thenallow a
precise operational denition of each commonfactor: a common factor
is that which is implemented bya specic pattern of techniques.
Therefore, the primarygoal of this study was the description of all
commonfactors by their idiosyncratic associations with
techniques.In this, we relied on the consensual knowledge of
psycho-therapy experts acting as referees who assessed
theseassociations step by step. Accordingly, we hypothesized
insecond line that rater variables (gender, age,
profession,allegiance to a psychotherapy approach) would inuencethe
assessments to a limited degree only.
METHODS
Selection of Common Factors and Specic Techniques
A recent comprehensive literature search identied allconstructs
discussed as non-specic or common factors oftherapeutic change in
psychotherapy research literature.Pfammatter and Tschacher (2012)
included all factors thatwere described by at least two authors.
For the presentstudy, we adopted this list of 22 common factors,
whichare dened in Table 1.Simultaneously, based on textbooks of the
four major
approaches of psychotherapy (cognitive behavioural ther-apy,
psychodynamic therapy, humanistic therapy andsystemic therapy), we
selected 22 standard techniques(Table 2) of these approaches
(numbers of factors andtechniques are equal by coincidence). Our
selection oftechniques was subjective. We selected techniques
thatrepresent the most characteristic procedures of the
majorpsychotherapy approaches, particularly those techniquesthat a
group of experienced psychotherapy researcherswould supposedly be
familiar with, even if a techniqueoriginated from a different
psychotherapy approach thanthe researchers own.
Survey
An internet-based survey consisting of the 22 commonfactors and
22 specic techniques was developed. Afterlogging into the system, a
participant was briefed on theobjectives of the study: to
investigate the relationshipbetween techniques and common factors,
with the ultimategoal of arriving at a taxonomy of common factors.
Onthe next page, as an initial common factor, TherapeuticAlliance1
was introduced and dened (Table 1). Theinstruction was: Please
assess how much, in your opinion,
this common factor is implemented by each of the
followingstandard techniques, and the participant was presented
thelist of 22 psychotherapy techniques. Adjacent to each of
thelisted techniques, a brief description of the technique
wasprinted, e.g.: Positive reinforcement technique: the
therapistcommends and rewards desirable behaviour of the
patient.For each technique, a 5-point Likert scale (not, little,
moder-ate, marked, strong) was provided to record the partici-pants
response. We assigned the values 2, 1, 0, 1, 2 tothe points of the
scales. The list of techniques was presentedinxed sequence in the
order of Table 2. This procedurewasrepeated on new pages until all
common factors had beenpresented to the participant, or until the
participantstopped the survey. The point of stopping was
book-marked so that it was possible to resume the survey at alater
time. A complete survey lasted approximately50min and contained 22
22 = 484 items per participant.
Participants
Experienced researchers of psychotherapy, most of whomwere also
active psychotherapists, were contacted viapersonal e-mails and
invited to participate as expert ratersin an internet-based survey
(using the platform Survey-Monkey). We contacted, in rst line,
German-speakingmembers of the Society for Psychotherapy Research,
andin second line, further psychotherapy researchers with
apsychiatric afliation. Most addressees had an academicbackground.
Of 140 researchers addressed, 68 nallyparticipated in the survey
(mean age 50.2years, standarddeviation (SD)=11.1; 47 (69%) men).
Non-responders didnot signicantly differ from participants with
respect togender, yet mean age of non-responders was
higher:54.6years; t(138) = 2.47, p< 0.05. Participants mean
profes-sional experience in psychotherapy research
(independentvariable Experience) was 18years (SD=11.0), and
currentactive psychotherapeutic work was 9h/week (SD=8.8).As for
their professional and scientic backgrounds (inde-pendent variable
Profession), 54 participants (79.4%) werepsychologists, nine
(13.2%) were psychiatrists, four (5.9%)were both psychologists and
psychiatrists and one (1.5%)was trained in another profession.
Professions of non-responders were not signicantly different
(chi2(3) = 2.37,p=0.50). Participants (variable Rater) noted their
predom-inant psychotherapeutic orientations (independent
variableAllegiance) as cognitivebehavioural (n=29,
42.6%),psychodynamic (n=19, 27.9%), eclectic (n=14, 20.6%),systemic
(n=4, 5.9%) and client-centred (n=2, 2.9%).
Statistical Procedures
Each participating rater assessed the associations between22
techniques and 22 common factors, i.e. he or sheresponded to a
maximum of 22 22 = 484 items. With
1In the following text, common factors will be printed bold,
tech-niques in italics
84 W. Tschacher et al.
Copyright 2012 John Wiley & Sons, Ltd. Clin. Psychol.
Psychother. 21, 8296 (2014)
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Table 1. List of common factors with denition given in the
survey; Relevance, intercepts of all ratings of a common factor
(test againstzero: * p< 0.05; ** p< 0.01; *** p< 0.001;
**** p< 0.0001); Explanation, % variance of a common factor
explained by all techniques (cf. text)
Common factor Denition Relevance Explanation
Therapeutic alliance Patient and therapist establish a trusting,
cooperative relationship;characterized on the therapist side by
afrmation and affectivewarmth towards the patient as a person
(interactional variables ofRogers, 1951). Alliance includes mutual
connectedness and consensusabout therapeutic goals and tasks (see
Bordins (1979) concept ofworking alliance)
0.17* 16.90
Mitigation of socialisolation
Patient experiences a reduction of social isolation and
alienation(according to Lambert & Ogles, 2004)
0.26** 24.72
Provision of anexplanatory scheme
Patient is offered a theoretical scheme which provides a
plausibleexplanation of her or his problems and which prescribes
aprocedure (ritual) for the resolution of problems (see the
commonfactor credible rationale (myth) by Frank, 1971)
0.03 22.04
Instillation of hope Patient forms the expectation that the
therapy will succeed and her orhis problems will be improving
(refers to the common factorsinstillation of hope by Frank (1971)
and induction of positivechange expectations by Grawe, 2004)
0.05 24.39
Readiness to change Patient develops the readiness to change her
or his situation orbehaviour (refers to the common factors
persuasion to change byTracey et al. (2003) and encouragement to
try new behaviours byLambert & Ogles, 2004)
0.04 19.91
Patient engagement Patient actively participates, is engaged in
the therapeutic process(see common factors client active
participation by Lambert &Ogles (2004) and patient role
engagement of the Generic Model ofPsychotherapy, Orlinsky et al.,
2004)
0.22** 23.71
Resource activation Therapist emphasizes and vitalizes
strengths, abilities and resourcesof the patient (see the common
factor resource activation by Grawe,2004)
0.04 27.90
Affective experiencing Patient experiences emotions and affects
that are associated with her orhis problems (see common factor
affective experiencing by Karasu,1986)
0.17* 29.81
Affective catharsis Patient expresses yet repressed feelings
(refers to the psychoanalyticcatharsis thesis)
0.14 29.44
Problemconfrontation
Patient is encouraged to face, experience and deal with her or
hisproblems (see the common factors encouragement to
faceproblematic issues by Weinberger (1995) and problem
actualizationby Grawe, 2004)
0.14* 35.75
Desensitization Patient experiences progressing attenuation of
emotional reactions toaversive stimuli (see the common factors
desensitization andextinction of anxiety-associated responses by
Lambert & Ogles,2004)
0.39**** 25.98
Corrective emotionalexperience
Patient learns that the real experiences in problematic
situations arenot as devastating as the imagined or feared
consequences (see thechange factor corrective emotional experience
originallyconceptualized by Alexander (1950) in the context
ofpsychodynamic therapies)
0.10 20.98
Mindfulness Patient develops the ability of nonjudgmental
awareness of her or histhoughts, perceptions and feelings. She or
he learns to be aware ofinner processes in the here and now without
judging them (refersto the Buddhist attitude of an
evenminded-accepting attention toall sensations, emotions and
thoughts)
0.43**** 17.00
Emotion regulation Patient learns to perceive, express and
control her or his emotionsmore adequately (refers to affect
regulation, according to Fonagyet al. (2002) the process by which
individuals inuence whichemotions they have, when they have them
and how theyexperience and express these emotions)
0.15* 22.75
(Continues)
85Taxonomy of Common Factors in Psychotherapy
Copyright 2012 John Wiley & Sons, Ltd. Clin. Psychol.
Psychother. 21, 8296 (2014)
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common factor as dependent variable and a sample of 68raters,
the dataset available for each common factor com-prised a maximum
of 22 68 = 1496 records. The inter-net-based survey, however, did
not enforce completedatasets, thus the actual number of responses
receivedfor a common factor ranged between 920 and 1338 records(see
the row Observations (n) in Table 3). In other words,dependent
variables had varying missing information inthe predicting
variables. Because of the expected missingdata and in order to
account for statistically dependentdata (each rater performed
repeated assessments), weapplied mixed-effects hierarchical
analyses to model thedependent variables (i.e. the common factors)
by theindependent variables (i.e. the techniques and
ratersdemographic variables). The software package used inall
analyses was JMP 9 (SAS Institute Inc., Cary, NC). Adataset of 22
techniques 68 raters was thus available
for each common factor and served as the basis for allsubsequent
analyses in approaches a and b.Approach a: in an initial modelling
approach, we
described each common factor by dening two separatedimensions,
Relevance and Explanation (Table 1). Thesedimensionswere
operationalized as follows: The dimensionRelevance was computed, in
each common factor as thedependent variable, by the intercept of a
model with onlythe variable Rater entered as a random effect
(approach a.1).The single ratings constituted level 1, Rater
identiedlevel 2 of the data. The intercepts operationalize the
overallrelevance of a common factor. These intercepts were
verysimilar in value to the mean of response (r=0.99), i.e. themean
of all single ratings a common factor received (ratingsranging
between 2 and 2). In the column Relevance ofTable 1,we listed these
intercepts. The interceptswere testedagainst zero, the midpoint of
the scales.
Table 0. (Continued)
Common factor Denition Relevance Explanation
Insight Patient develops awareness of her or his problems and a
conception oftheir causal relation and their relation with
recurring patterns of her orhis behaviour (see the common factors
foster insight/awareness byGrencavage & Norcross (1990) and
motivational clarication byGrawe, 2004)
0.03 31.51
Assimilatingproblematicexperiences
Patient approximates problematic experiences to pre-existing
owncognitive schemata and is thereby able to be more familiar
withthem (refers to the distinction introduced by Piaget
betweenAssimilation and Accommodation as to two different types
ofdeveloping and changing cognitive representations of the
world)
0.22** 20.64
Cognitiverestructuring
Patient gradually accommodates conceptualizations of
problems,acquires new perceptions and thinking patterns, which
promoteunderstanding and integration of problematic experiences
(seecommon factor cognitive mastery, Karasu, 1986)
0.16 26.78
Mentalization Patient learns to understand herself or himself
and others in terms ofmental states (i.e. feelings, thoughts,
intentions) and therebydevelops the ability of anticipating the
behaviours and reactions ofothers (theory of mind) (see the
capacity to read, (. . .) predict andexplain other peoples actions
by inferring and attributing causalintentional mind states to them
(Fonagy et al., 2002))
0.24** 31.25
Behaviour regulation Patient learns new behavioural responses
and social skills to modifyhabits and to manage and control actions
(see the common factorsbehavioural regulation by Karasu (1986) and
learning of masterybehaviours by Lambert & Ogles, 2004)
0.24** 35.12
Mastery experiences Patient gathers successful coping
experiences (see the commonfactors mastery efforts and success
experience by Lambert &Ogles (2004) and coping by Grawe,
2004)
0.25** 33.25
Self-efcacyexpectation
Patient increases her or his sense of personal inuence and
control(see the common factor changing expectations of
personaleffectiveness by Lambert & Ogles (2004), derived from
Bandurasconceptualization of self-efcacy)
0.22** 34.27
New narrative aboutself
Patient develops a new sense of coherence regarding her or his
past,present and future life, as well as her or his being in the
world (seethe common factor construction of a
meaning-generatingnarrative by Jorgensen, 2004)
0.21** 25.64
Table 1. (Continued)
86 W. Tschacher et al.
Copyright 2012 John Wiley & Sons, Ltd. Clin. Psychol.
Psychother. 21, 8296 (2014)
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As a second dimension, we assessed Explanation. Wecomputed
models with Rater entered as a random effectand Technique as the
xed effect (approach a.2). Thecorresponding explained variances
operationalize thedegree of differential explanation of each common
factorby the set of techniques. Finally, to integrate the two
dimensions of approach a, the ratio Relevance/Explanationwas
computed which is positive if both Relevance and Ex-planation
assume positive values.Approach b addressed the primary goal of the
study by
comprehensive modelling including the inuence of
ratercharacteristics. We modelled each of the 22 common factors
Table 2. List of techniques with denition given in the
survey
Technique Denition
Positive reinforcement technique Therapist praises/rewards
desired, adequate patient behaviour.Exposure with response
prevention Therapist confronts patient in imagination or in vivo,
gradually or by ooding,
massed or in intervals with a problematic situation and prevents
escape.Role play technique Therapist simulates difcult social
interactions in a play with patient as
participant, and instructs, models and corrects the
performance.Problem-solving training Therapist teaches patient to
identify and dene the problem, to systematically
generate and evaluate alternative problem solutions, to
implement and verifyselected problem solution.
Reality testing Therapist encourages patient to test the
evidence for the validity ofdysfunctional thoughts and beliefs,
runs behavioural experiments andprovides alternative
explanations.
Free association technique Therapist encourages patient to talk
about whatever comes to her or his mind.Therapeutic abstinence
Therapist deliberately does not comment statements, disclosures or
behaviour
of patient.Transference interpretation Therapist links
patienttherapist relationship to other interactions of patient
to
point out recurring problematic themes in her or his
relationships.Resistance interpretation Therapist draws attention
to the patients opposition to or avoidance of certain
topics, experiences or feelings by pointing out evasions, sudden
thematic shiftsor behavioural inconsistencies.
Verbalization of emotionalreactions
Therapist listens carefully to what patient is saying, uses
empathic statements,repeats back (paraphrases), explores its
personal meaning and reects theinternal frame of reference
(mirroring).
Focusing Therapist draws attention to unexpressed feelings,
promotes deeperexperiencing, encourages patient to explore and
express feelings.
Empty-chair and two-chairtechnique
Therapist guides patient to speak to an empty chair for unnished
business, orengages patient in a two-chair dialogue for analyzing
and resolving innerconicts.
Creative expression technique Therapist encourages patient to
use creative media to actualize experiences andexpress
feelings.
Circular questions technique Therapist explores the meaning of a
problematic behaviour of a family memberfor another family member
with a third family member.
Sculpture work Therapist asks the family to spatially illustrate
the familial relationships(afnity, distance, hierarchical
structure) by building a sculpture.
Paradoxical intention technique Therapist offers a new
interpretative framework (reframing), assigns a positivemeaning to
the problem (positive connotation), invites patient to
deliberatelyshow the problem behaviour (symptom prescription) or
offers lots of problemsolutions (confusion technique).
Prescription of rituals Therapist prescribes formalized and
symbolic actions that disrupt problematicbehaviour.
Reecting team technique A team of experts monitors therapy and
discusses the observations withparticipants.
Progressive muscle relaxation Therapist guides patient to
rhythmically and sequentially contract and relaxdifferent groups of
muscles.
Hypnosis Therapist asks patient to bring up pictures or scenes,
or induces hypnotic tranceby verbal suggestions and motoric
procedures.
Biofeedback training Therapist guides patient to deliberately
inuence and control physiologicalprocesses by feedback signals,
discriminative learning and relaxation techniques.
Counselling Therapist gives advice.
87Taxonomy of Common Factors in Psychotherapy
Copyright 2012 John Wiley & Sons, Ltd. Clin. Psychol.
Psychother. 21, 8296 (2014)
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Table3.
ad.R
esultsof
mixed-effectsmod
ellin
gof
each
common
factor.C
ommon
factor,d
ependentvariable;techn
iquesandratercharacteristics,xedeffects:*p