The Efficacy of Rational Emotive Therapy

From:Lyons, Larry C. & Woods, Paul J. (1991).The efficacy of rational emotive therapy: A quantitative review of the outcome research.Clinical Psychology Review, 11, 357-369.

-q O6j?:A9a(i s.}!A+L0We thank Wendy A. Morris for her assistance in preparing this manuscript. Without her inestimable help, this project would not have come to fruition.内蒙古心理网 h{0a&Kxl

Larry C. Lyons, MA was a Research Associate at the Hollins Communications Research Institute when this article was published in Clinical Psychology Review. He is currently both a consultant and with a private firm in Manassas, Virgina.内蒙古心理网E~3bPL$U0N*R I_)y

LPF O+oXRe0Paul J. Woods Ph.D.is a Professor of Psychology (Emeretus) at the Department of Psychology at Holllins College, and director of the Institute for Rational Therapy and Behavioral Medicine in Roanoke Virginia

Address request for reprints of this article, coding manual or list of studies used in this quantitative review to the second author at:

:KM$z C r0Paul J. Woods Ph.D. Institute for Rational Therapy and Behavioral Medicine, 5541 Florist Road Roanoke, Virginia

Abstract内蒙古心理网G"Cs u
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PG`$}*}TZ1Z4]%sG]Gd0The results indicated that subjects receiving RET demonstrated significant improvement over baseline measures and control groups. The results showed no significant differences in effect size between those studies which used psychotherapy clients or students as subjects. Effect size was significantly related to therapist experience and to duration of the therapy. The results indicated that those comparisons which were rated high in internal validity had signficantly higher effect sizes than medium validity studies. Outcome measures rated as low in reactivity had significantly higher effect sizes than more reactive measures.内蒙古心理网tU.x+T
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Contrary to other reviews using the narrative review method, RET was found to be an effective form of therapy. However, this conclusion was tempered by methodological flaws of the studies reviewed, such as lack of follow-up data and information regarding attrition rates.内蒙古心理网4DJO1dQUE

Rational Emotive Therapy (RET) has become one of the most accepted forms of Cognitive Behavior Modification since its initial development in the late 1950's and early 1960's. (Ellis, 1957; 1962; Gregg, 1973). Narrative reviews have either supported RET's efficacy or criticized its usefulness. Using a quantitative review method (meta-analysis), this study examines the efficacy of RET and addresses many of the criticisms advanced by previous reviews of RET.内蒙古心理网ic@y,rl\

Ledwidge (1978) reviewed 13 outcome studies comparing Cognitive Behavior Modification (CBM) to Behavior Therapy. Of the 13 studies, six were based on either RET or Systematic Rational Restructuring. He concluded that although these studies suggest no differences between behavior therapy and Cognitive Behavior Therapy (and by extension RET), this was only apparent because none of these studies used a clinical sample. On the basis of these findings, Ledwidge concluded that behavior therapy was the superior form of treatment.内蒙古心理网|`m4P/^7vU

Sh7O A~FTyfA0DiGiuseppe and Miller (1977) reviewed 22 studies which examined the effectiveness of RET or a closely related therapy. These studies were categorized in two sets: comparative studies, which compared RET to some other psychotherapy; and non-comparative research which examined RET to baseline scores or against some form of control. DiGiuseppe and Miller concluded that many of the studies had a variety of methodological problems typical of most psychotherapy research. They found RET to be considerably more effective than no treatment control and baseline scores.内蒙古心理网'B/K(k3A~L

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?^1Y%[`9J{0Zettle and Hayes (1980) reviewed 35 studies which investigated the theoretical assumptions, individual treatment components, and overall effectiveness of RET. They claimed all available outcome research were either unsystematic case studies or consisted of analogue research. Less than half (16) of the 35 studies were outcome experiments. Based on these 16 studies, the authors concluded that the clinical efficacy of RET was not demonstrated. Prochaska (1984) surveyed eight studies which examined the effectiveness of RET. From this limited sample, he concluded that these studies demonstrated only equivocal results and the most positive application of RET was for reducing common anxiety. Based on their review of 47 RET outcome studies, McGovern and Silverman (1984) concluded that these studies supported the efficacy of RET.内蒙古心理网!uu%T*Mv$]?R

Reviewers of RET outcome literature have raised many criticisms regarding RET outcome research. One such criticism involves the issue of "elegant" vs. "inelegant" RET (Ellis, 1980). Ellis describes inelegant RET as other forms of cognitive behavior modification, while "elegant" RET refers to the specific approach advocated by Ellis and others. Similarly, Wessler (1983) claimed the researcher frequently misunderstands the therapeutic approaches of RET, or else mislabels or misrepresents the procedure until it is no longer RET. Thus, the question to be investigated is : Does the degree of similarity of the treatment to RET influence effect size.内蒙古心理网j8{
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Several reviewers have criticized the methodological quality of RET outcome studies (e.g., DiGuiseppe and Miller, 1977; Ledwidge, 1978; Prochaska, 1984; Zettle and Hayes, 1980). Their concerns include low percentage of male subjects; subject solicitation; students vs psychotherapy clients; the number of subjects per comparison; subject and therapist assignment to treatment or control groups; therapist training; treatment duration; individual vs group therapy; and reactivity and type of outcome measure.

Another area of investigation is the issue of using students versus clinical subjects. Ledwidge (1978) and Zettle and Hayes (1980) note in their reviews that most RET studies used students volunteers as subjects. They question the external validity of these studies, since the problems assessed may not be applicable to the typical client. While RET may indeed prove effective with students suffering from test anxiety, it is possible that RET may be relatively ineffective when dealing with more serious clinical problems, like depression, or agoraphobia. In other words, are there differences in effect sizes among studies which use students as opposed to psychotherapy clients?内蒙古心理网7T'VwMBdG

Reviewers disagree on the therapeutic effectiveness of RET. This point constitutes the core of the present review, what is the therapeutic efficacy of RET? This point is difficult to answer in the context of an individual study or the narrative review, because reviewers can reach very different conclusions given the same evidence. The quantitative review format directly address the question of the therapeutic efficacy of RET without reviewer bias.内蒙古心理网r T8O5U'm aKw1v9K

Method

SelectionofStudies:内蒙古心理网2r,Lv!T6X7PW

ThePsychologicalAbstractsandDissertationAbstractsInternationalfrom 1972 to 1988 were searched for relevant studies. In addition, the reference lists of the obtained studies and the previously mentioned reviews were scanned for additional material. A list of the studies used in this meta-analysis can be seen in the appendix following this article.内蒙古心理网bPE]b,j6v

$mT4|0g-q/eKM S0Each study had to meet the following inclusion criteria:内蒙古心理网^cYy.v4pF

(1) At least one treatment group received Rational Emotive Therapy, or a treatment which used elements of RET.

(2) The study compared RET to a baseline measure, a control group, or other type of therapy.内蒙古心理网X;V9k N&v

(3) The study used a quantitative statistic which could be converted to an effect size estimate.

(4) The study gave the number of subjects in each treatment or control group.

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Studies were rejected because of uninterpretable statistics, or because insufficient information regarding treatments, or experimental procedures were presented. Single subject designs and case studies were also excluded.

EffectSizeEstimation内蒙古心理网
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/w&| v$M+o%ORB"^0Each comparison of RET to the baseline assessment, control, or treatment groups was expressed in terms of the Standardized Difference between Mean Scores (d; Cohen, 1977). Some researchers (e.g., Glass 1976, 1977; Smith & Glass, 1977; Smith et al, 1980) advocate using the comparison group standard deviation as the denominator ford. However, there are two reasons against using the comparison group standard deviation, first, the within-subjects standard deviation has approximately half the sampling error of the comparison group; second, the within-subjects standard deviation generally provides a more accurate estimate of the populations(Hunter et al, 1982). Afterdis calculated for each study, the effect sizes are averaged.内蒙古心理网q2v0O)fxlf2H

4sXL$g/e|)]0Where possible, effect sizes were obtained by directly calculatingdfrom the means and standard deviations reported in the individual study. Otherwisedwas calculated fromt,f,r, or a probability value using procedures taken from Cohen (1977) or Hunter et al (1982). If the comparison was taken from a two-way ANOVA, the statistic was first converted to theetastatistic using an algorithm taken from Hasse (1983). This correlation coefficient was then converted todusing procedures outlined by Cohen (1977) and Hunter et al (1982).

When the exact probability level was given, this value was converted into azscore and then converted to a point-biserial correlation. Adwas then estimated using the previously mentioned procedures outlined by Cohen (1977) and Hunter et al (1982). Unfortunately in some studies, an exact statistic was not available. An approximation procedure was used to estimated. Where nonparametric statistics or multiple comparison procedures (e.g., Duncan's Multiple Range test or Newman-Keul's test) were used, the associated probability value (.05, .01, or .001) was converted first to azscore and then to adstatistic using the previously discussed procedures.

If the study only stated a significant difference, the associated probability value was set to .05, and the appropriatedstatistic was calculated using the above conversion algorithms. Similarly, where the term no significant difference was reported, the effect size was assumed to be 0.内蒙古心理网0a&h3u
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-|sLn"?:e:X1D+e0In comparisons ofd's derived from test statistics (e.g.,t,F, or means and standard deviation) to those derived from probability values taken from the same statistics, the effect size estimates of the test statisticdwere less conservative estimates than those derived fromp.内蒙古心理网6Q cz? P3z

QYz2k/zD+F0The majority of the studies included in this meta-analysis used more than one outcome measure. Other meta-analyses (e.g., Smith et al, 1980) included all nonredundant measures in the analysis. The main problem with this approach is the analysis is based on on dependent effect sizes biasing the results by giving more weight to those studies with multiple effect sizes. To avoid this bias, the present study averaged the effect sizes to produce a single statistic within each comparison of RET, preserving the independence of each comparison.内蒙古心理网#lF-e6@2^"K
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CodingProcedures内蒙古心理网y0E.[9zv

After converting the study statistics to effect sizes, study characteristics were examined and coded using a 28 variable coding scheme. A complete list of the articles and dissertations used in the present meta-analysis is available from the author for a $5 fee to cover printing, postage, and handling. These coding variables included the year of the comparison (either publication or acceptance date), and level of therapist training.

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1. Neurotic: subjects had the following problems: personal growth, achievement problems, social anxiety, excessive anger, assertion, depression, students with behavior problems, speech anxiety, potential school and college, dropouts, etc.
2. Phobic: subjects were diagnosed as suffering from some form of phobia, including simple and complex phobias, agoraphobia, etc.
3. Normal: participants had no immediately discernible problem
4. Emotional/Somatic: subjects with asthma; sexual dysfunction; insomnia; obesity; migraine headaches; chronic heart disease; and individuals on home dialysis
5. Unknown/Unclassified: participants who could not be classified into any of the previous categories, it also included those problems where numbers did not merit a separate classification group.

!?(YhfBoh-O"V/a0To determine the effectiveness of RET against other therapies, comparison groups were coded according to the therapies they received:内蒙古心理网i$wu$p i@`c

1. Baseline comparison: the pretreatment measure taken at the start of therapy.
2. No Treatment Control (NTC): comparison against a group not receiving therapeutic intervention.
3. Waiting List Control (WLC): groups whose participants did not receive therapy but who were given the expectation they were on a waiting list for treatment.
4. Attention Control/ Placebo (ACP): groups where relaxation or a placebo treatment was given in order to control for non-specific treatment effects.
5. Cognitive Behavior Modification (CBM): therapies using the techniques and theories of behavior and personality change based on Bandura (1977), (1977), Mahoney (1974) and others.
6. Behavior Therapy: therapies using principles and procedures based on Learning Theory, including treatments based on Systematic Desensitization, exposure techniques, behavior modification, and other conditioning based procedures.
7. Other/Unclassified: other therapies including psychodynamic, Gestalt, humanistic, Adlerian, Reality therapy, vocational/personal development counseling, and undifferentiated counseling. There were very few studies using these therapies, making it impossible to discern any reliable difference between groups.

To determine whether the effectiveness of RET was a function of the degree of similarity to strict Rational Emotive Therapy, two separate coding schemes were used. First, RET studies were classified into comparisons using strict RET methods; Systematic Rational Restructuring or other similar therapy; or CBM treatment procedures which relied on many RET techniques. Second, a rating scheme was derived to assessed the degree of similarity of the treatment group's therapy to RET. This rating scheme was a six point likert scale from 0 (no elements of RET), to 5 (all elements of RET). The studies were rated on various salient features of RET, such as identification, disputation, and modification/replacement of irrational beliefs, homework assignments, and collaborative empiricism between therapist and client, etc. Both the treatment and comparison groups were coded in this manner.内蒙古心理网:B3M?2nx|P

Subject and therapist assignment to treatment and comparison groups were also coded. For the subjects, the categories included内蒙古心理网,Ct;vy.Z_$~

1. Random Assignment, where the participants were assigned randomly to either the treatment or comparison groups
2. Matching, where a subject was matched with another from the opposite group
3. Non-Random Assignment, where ex-post facto matching, covariance adjustments, and equating on pretest scores, or order of participation in the study was used
4. Unknown, including those studies which did not mention the method of subject assignment to groups.

Therapist assignment used a similar coding procedure with an additional category of comparisons using a Single Therapist for each treatment condition.内蒙古心理网g(MYcR0nP$F0N

:]7D9~t:^A#a0Subject recruitment was also coded, using procedures adapted from Smith et al (1980). Studies were classified according to the following criteria:内蒙古心理网B.\;_gKge%zw

1. The participants recognized the existence of a problem and sought help
2. The subjects responded to an advertisements
3. Subjects were directly solicited by the therapist, typically by offering treatment to psychology students with extreme scores on a criterion measure
4. Individuals were referred for treatment by a third party
5. Participants were committed for therapy, with no choice, as in court ordered treatments.

2N#O#g3{?0A rating scheme was developed to assess the effect of variations in internal validity on effect size.

1. High validity: random assignment, for subjects and therapists, had a low estimated attrition rate (¾ 15% dropout rate), and used outcome measures deemed low in reactivity
2. Medium internal validity: random assignment, or matching for participants and therapists, but had high estimated attrition rates (>15%), or did not mention the dropout rate, and used outcome measures rated medium or low in reactivity
3. Low internal validity: non-random assignment (other than matching), had a high estimated dropout rate or did not mention the attrition rate and medium or highly reactive outcome measures.

uK@3_V7o _0To assess outcome measure characteristics of the sample, two coding schemes were used according to the type of test used for assessment. Coded outcome measures included:

1. Fear and anxiety measures, like Behavioral Approach Tests, and anxiety questionnaires
2. Standardized test and measures in common use, like the Irrational Beliefs Test (Jones, 1968), and the Beck Depression Inventory (Beck, 1978)
3. Physiological measures, like galvanic skin response, heart rate, and EEG;
4. Unclassified including those measures which could not be assigned to any of the previous categories, or there were not enough comparisons to merit a separate classification.

Test reactivity refers to the degree of similarity between the treatment and the test measures. The reactivity of the outcome measures was assessed using a rating scheme adapted from Smith et al (1980).

1. Highly reactive measures revealed or had a direct and obvious relationship with the treatment. This category also included nonblind symptom ratings by the therapist ; behavioral approach tests assessed by the experimenter, and in the case of RET oriented treatments, irrational beliefs tests
2. Medium reactive measures were defined as standard test and measures with a minimal connection to the therapy. Examples included the MMPI and the Beck Depression Inventory and the State-Trait Anxiety Inventory (Spielberger, Gorsuch, & Lushene, 1970) for therapies not explicitly treating depression or anxiety
3. Low reactive measures included those test and measures not easily influenced by the parties involved. Examples include galvanic skin response and other physiological measures; grade point average; blind ratings and decisions; and blind discharge from hospital.

Results

D2b:{ o~y,o8S0Table 1 presents several demographic characteristics of the studies examined in the present quantitative review. Year of publication ranged from 1970 to 1988, with a median of 1978.5. Publication year was not related to effect size. The median training level for the therapists was 5.000 (PhD candidate or psychiatric resident). Therapist training was significantly related to effect size. The number of subjects per comparison was also significantly related to effect size, smaller number of participants in each comparison group was related to larger effect sizes. The mean age of the subjects, and the percentage of male subjects were not related to effect size内蒙古心理网 `"o/s
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w1t7g:u?6D.qA*Q;M0No significant differences were found in terms of effect sizes between studies using psychotherapy clients or students as participants (t(234) = 0.710, ns), as shown in Table 2.

Table 2.
PIqB}+m?[0TypeofSubjectsinRETOutcomeStudies

Significant differences were found between the different diagnostic groups (F(4,231) = 6.443,p< .001). as shown in Table 3. Comparisons using participants with emotional-somatic problems tended to have significantly higher effect sizes than those comparisons in the other diagnostic categories. Comparisons in the neurotic category had significantly higher effect sizes than those comparisons using normal subjects. No other difference between comparisons was significant.内蒙古心理网0V#v9]P&]!N

Table 3.内蒙古心理网&]?
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SubjectDiagnosis

Table 4 shows other study characteristics associated with the sample. The degree of similarity of the therapy to RET was found not to be related tod, for both the treatment and comparison groups. Duration of therapy was found to be significantly related to effect size, in terms of the number of hours and weeks of therapy .内蒙古心理网5k"_1h#\v1V A I

&?9FoGkc2w"a8M5St0Table 5 presents the effect size estimates broken down by comparison groups. To facilitate the analysis and understanding of these results a Binomial Effect Size Display (BESD; Rosenthal & Ruben, 1982) was also employed.

6s {3U8N+y{ z#I${P0The BESD displays the change in improvement rate (or success rate, survival rate, etc.) attributable to a certain treatment intervention. In other words, the BESD is the estimated difference in the probabilities of improvement between the treatment and control, or between pre- and post intervention. It is defined as BESD = (.50-r/2) to (.50+r/2), whereris a point biserial correlation. For example, an effect size ofd= .872, (r= .40), when expressed as a BESD, shows that the improvement, or improvement rate prior to intervention is 30%, while after the intervention the improvement rate increases to 70%.内蒙古心理网6N|9n'gi!v.P(A\

.b?c.o7t@0The overall effect size was .949. Using the BESD, 27.2 % of the sample would have demonstrated significant improvement before therapy. Following RET, 72.8 % of the sample demonstrated significant improvement over those subjects not receiving RET.内蒙古心理网7\6~ Y-U/_n@6Yy

suy1o/q8P0In comparing RET to all other treatment conditions, a one way ANOVA indicated significant differences in effect sizes between the various comparisons (F(6,229) = 9.624,p< .001). A Duncan's Multiple Range test indicated that comparisons with baseline conditions had significantly higher effects sizes than all other comparison groups, except for those comparisons with a waiting list control group. Compared to baseline, the mean effect size was 1.371. Using the BESD indicator, the pretherapy clinical improvement rate was 21.5 %. Following RET intervention the improvement rate was 78.5 %.

_?hC;C0Comparisons with therapies using CBM or Behavior Therapy demonstrated the lowest mean effect sizes of the sample. A Duncan's Multiple Range test indicated that CBM and Behavior Therapy had significantly lower effect sizes than any of the other treatment conditions.

&V%Xx.`"W,a0Table 6 shows the mean effect sizes for individual and group therapy formats. No significant differences were found between comparisons using an individual or a group therapy format (t(234) = 0.940, ns).内蒙古心理网'z|.a
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fo+YF9g9w0Tables 7 to 9 present the analyses of the methodological characteristics of the sample. Table 7 presents the subject and therapist assignments to treatment and comparison groups. No significant differences were found among any of the subject (F(3,232) = 0.580, ns). or therapist assignment categories (F(4,231) =1.804,ns).内蒙古心理网qr)P$K0{

Table 8 presents the subject solicitation data. Significant differences between solicitation categories were found (F(4,226) =3.020,p< .02). Participants referred by a third party had significantly higher effect sizes than any other solicitation category. No other differences were found to be significant.内蒙古心理网"^E3k^?Y

Table 9 presents the internal validity rating of the sample and the associated effect sizes. Significant differences were found between the internal validity categories (F(2,233) = 3.472,p< .05). A Duncan's Multiple Range Test indicated that comparisons with high internal validity rating had significantly higher effect sizes than comparisons with medium internal validity ratings. No other comparison was found to be significant.

table 10 presents the breakdown of effect sizes by the type of outcome measure. Significant differences were found among the effect sizes associated with different outcome measures (F(3,232) = 31.064,p< .001). Physiological measures had significantly higher effect sizes than all other outcome measures. The Unclassified category had a significantly greater mean effect size than either Fear/Anxiety, or Standard Test Measures. Fear/Anxiety and Standard Test Measures were not significantly different from each other.内蒙古心理网&wuGC|
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}[Q0] ]i{0Table 11 presents the breakdown of effect sizes by the reactivity of the outcome measure. Significant differences were found between reactivity ratings (F(2,233) = 14.896,p< .001). A Duncan's Multiple Range Test indicated that outcome measures rated low in reactivity had significantly higher effect sizes than measures rated medium or high in reactivity.

ja%O}j3x)t0The results demonstrated that RET is an effective form of therapy. The efficacy was most clearly demonstrated when RET was compared to baseline and other forms of controls. The differences between comparisons of RET to CBM and Behavior Therapy were not significant.内蒙古心理网m4M#`$F0zj g

One general criticism of RET outcome studies have been the great number of analogue studies. Ledwidge (1978) and Zettle & Hayes (1980) claimed that by using student volunteers, the therapeutic efficacy of RET was not demonstrated. Based on the present results this criticism is not warranted. No significant differences were found between comparisons of student and clinical subjects. Most of the studies involving students were investigating genuine problems. While these problems may not be as severe as those seen in clinical settings, if RET was not an effective form of therapy, or was not effective for more severe problems, a disparity between results found with students and psychotherapy clients would have been found.

DUQg]8K8{0Reviews with a definitive allegiance to RET (e.g., DiGuiseppe & Miller, 1977) criticized many RET outcome studies for using postgraduate students as therapists. This clearly remains a problem. The majority of therapists in the studies reviewed were PhD Candidates, with relatively little experience compared to professional therapists. The results suggest that therapist experience is an important variable in influencing the effectiveness of RET.内蒙古心理网|2wy,i?$O9uWg u w2L

These results with therapist experience vary somewhat from Miller & Berman (1983). In their quantitative review of CBM studies, therapist experience was not related to effect size. One explanation of this difference lies in how Miller & Berman (1983) assessed therapist experience, which was measured in years, whereas a rating scheme was used in the present meta-analysis. A rating scheme was used in the present study was used because information regarding exact clinical experience was generally not available. If more detailed information was readily available, results similar to the Miller & Berman (1983) may have been found.内蒙古心理网9V5ih5L.t|

Given this difference with previous results, the finding of the present quantitative review indicate that the more experienced the therapist, the more effective the treatment. There is, however, one qualification of this statement, there is no real guarantee that the therapy being used was actually RET as practiced and taught by the Institute of Rational Emotive Therapy. As Wessler (1983) noted, it is very possible that procedures thought to be RET may not have been strict RET, but rather methods subject to experimenter interpretation. An attempt was made to control for this factor by using RET similarity ratings of both the treatment and comparison therapies. However no relationship between effect size and the number of RET principles actively used during the treatment was found. It should be noted that the range of the ratings was restricted. The majority of treatment therapies having at least several elements used in strict RET procedures. Thus the true relationship between similarity of the treatment treatment to RET may be somewhat obscure. One recommendation is that researchers should publish more detailed descriptions of their procedures, or at least make available to reviewers, detailed treatment manuals. This allows a reviewer to determine whether the procedures involved were actually "elegant" RET or "inelegant" procedures.

X.E5| r `)P%V/r0One of the criticisms made by DiGiuseppe & Miller (1977), and McGovern & Silverman (1984) was that the short duration of the treatments may limit the effectiveness of RET. The results confirm this criticism. Larger effect sizes were related to therapy duration. The longer the therapy, the larger the effect size. However, the magnitude of the correlations was not very large, accounting for only 11.3% of the variance in effect sizes for duration in hours, and 3.5% of the effect size variance for duration in weeks. Given this limitation, there is a relationship between duration and therapy effectiveness. This is clearly demonstrated with those studies which used only one or two treatment sessions, these studies had the lowest effect sizes.内蒙古心理网8C9P5cG2X.v&n7z

9F
T|4P4mw#x|U0The present study attempted to examine methodological criticisms in several ways. First, an attempt was made to relate effect size to attrition or dropout rates. However, no detailed analysis of the attrition rates was possible since only nine of the studies reported attrition rates, thereby biasing the results of the present quantitative review. It is not defensible to assume that all 61 of the studies which did not report on attrition had zero dropout rates. Therefore the conclusion that RET is an effective form of therapy must be tempered with the consideration that this conclusion is only tenable for those individuals who manage to complete therapy.

It should be noted that in order to use a coding procedure based on Smith et al (1980)'s internal validity rating scheme, it was necessary to have a rough approximation of attrition rates. Attrition was estimated by examining the degrees of freedom and sample sizes for the RET and comparison groups before and after therapy.

'aL J#oi^0This estimate was considered adequate for judging internal validity, since there were other factors involved in the validity ratings, for example subject and therapist assignment,and test reactivity. It is invalid to use these attrition estimates as data in a separate analysis. Differing results could have occurred if the actual attrition rates had been reported.

dBd w%{0It is of interest to note that those studies judged high in internal validity also tended to have high effect sizes. The obvious implication is that well conducted studies most clearly demonstrate the effectiveness of RET procedures.内蒙古心理网yt1H5i
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Another methodological factor which was neglected by many studies was the follow-up status. The majority of studies (81.4%) did not report on follow-up data. Therefore any determination of the long term effectiveness of RET could not be made.

It is critical to report the previously mentioned factors. Not only does this give an indication of what the long term effectiveness of a therapy, it also gives indication of how difficult the therapy is to complete. One cannot truly determine the effectiveness of a therapy if a significant percentage of the clients drop out before completing therapy.

;{!z]9mHd0Contrary to what was expected, the reactivity of the outcome measures indicated that larger effect sizes were associated with measures low in reactivity. These results are different from Dush, Hirt & Schroder (1983). They examined this variable in the context of a meta-analysis of studies which used some form of self statement modification. These results are also different to what was found by Smith et al (1980). Both of these studies found positive relationships between test reactivity and effect size.内蒙古心理网t2L|`A

L7[aW8[?0One explanation of the differences is that while RET studies used reactive measures of irrational beliefs, they also included less reactive measures of adjustment, such as locus of control,and anxiety measures. The net outcome was that the average reactivity for the present analysis was lower than in the previously mentioned quantitative reviews.

Given the previously mentioned limitations to the present quantitative review, these results suggest that RET is an effective form of therapy. Compared to baseline assessments, and control groups, those individuals receiving RET demonstrated significant improvement. These results do not support the Zettle & Hayes (1980) conclusion that there is little evidence for the clinical efficacy of RET. In contrast, RET was shown to be an effective form of therapy. Perhaps it is time to stop the needless and inefficient discussion of the efficacy of this therapy. Rather, a better focus of investigations and reviews would be to determine which factors, or combinations thereof contribute most to the effectiveness of RET.内蒙古心理网oZ [9Xf1s X

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