Meta-Analysis

Why Meta-Analysis?

There is an urgent need for reliable summaries of primary research in music therapy.

1. Music therapists can not keep up with reading all of the published literature.

2. Music therapists need to be able to answer the basic question: Is music therapy effective?

What is Meta-Analysis?

Meta-Analysis (MA) is a form of survey research in which research studies, rather than individuals are surveyed.

Data are statistically analyzed using special statistics.

Patterns of results are reported.

In essence, MA is a form of research synthesis.

Meta-Analysis

“…meta-analysis provides a bird’s eye view of the landscape. By studying the landscape from an aerial view, one can discern patterns and make conclusions not possible when viewing the landscape from the ground.”

Effect Size

A measure that gives an indication of the size and variability of the phenomenon under investigation.

Various types of tools are used to collect data on a single phenomenon (anger, depression, physical endurance), and MA statistics compute a standard effect size for each type of data so that they can be compared numerically.

Effect size allows for a common language to describe both magnitude and direction of effect.

Advantages and Strengths

MA is a rigorous method in its own right, thus validity is increased.

MA uses a more sophisticated approach than descriptive methods of literature review.

Systematic procedures used in MA and the use of standardized computerized database for storage allows researcher to work with massive amounts of data.

MA clarifies areas of future research.

Disadvantages and Weaknesses

More labor-intensive and time-consuming than traditional methods.

Mechanistic and limited; can not get at certain nuances of the research studies.

Sampling of studies used in MA may be biased because journals tend to accept studies that have significant findings and reject those that do not.

Disadvantages and Weaknesses

Some studies do not provide enough data for inclusion in MA.

Comparison of apples and oranges? Can we compare disparate studies (those which use different measurement tools, subjects, and definitions of variables) in a meaningful way?

Qualitative studies can not be included in MA in a meaningful way.

MA in Music Therapy

Standley (1986) - MTx and medical and dental Treatment; 55 variables

d = .98 for all variables

sources of variability – patient dx and symptoms, sample size, function and type of music, and type of dependent measure

MA in Music Therapy

Standley (1992) - update of original study; 129 variables

Standley (2000) – update; 232 variables

MA in Music Therapy

Standley (2002) – MTx and neonates; 10 studies

d = .83

effects remained constant across birth weight, method of music therapy, volume, gestational age, and length of stay

MA in Music Therapy

Koger, Chapin & Brotons (1999) – MTx and patients with dementia; 21 studies

d = .78

source of variability in type of intervention, length of treatment, training of the therapist, could not be determined

MA and Music Therapy

Silverman (2003) – MTx and psychosis; 19 studies

d = .71

lack of homogeneity in effect size across studies; effects were consistent for live vs. recorded music and “structured groups vs. receptive music listening”; classical music less effective than non-classical

MA and Music Therapy

Dileo & Bradt (2005) – Medical music therapy; 184 studies

Research questions (from book)

MA and Music Therapy

Pelletier (2004) – MTx and stress reduction; 22 studies

d = .67

effects of music and music-relaxation in reducing arousal associated with stress

Whipple (2004) – MTx with children and adolescents with autism; 9 studies, 12 dependent variables

d = .77

MA and Music Therapy

Gold, Voracek & Wigram (2004) – MTx with children and adolescents with psychopathology; 11 studies

ES = 61

largest effects for clients with developmental disorders (compared to emotional disorders), psychodynamic and humanistic approaches (compared to behavioral), behavioral and developmental outcomes (compared to social skills and self-concept)

Conducting a Meta-Analysis

1. Determine focus of study2. Identify appropriate studies for inclusion (books,

journals, theses, and unpublished work)3. Code the studies that meet criteria for inclusion

(sample size, dependent variables, types of dependent variables, measurement tools, type of treatment, etc.)

4. Calculate the effect size5. Treat homogeneity6. Compare and combine effect sizes7. Evaluate the importance of the obtained effect sizes