Chapter 4: Results
4.2 Results: Effects of music therapy
4.2.1 Session analysis: Main effects and interactions
4.2.1.7 Number of events of spontaneous turn-taking
4.2.2 Supplementary analyses of parent pre- and post-intervention questionnaires 4.2.2.1 Analysis of the quantitative data
4.2.2.1.1 Analysis of the Likert-type questions 4.2.2.1.2 Analysis of the ‘yes/no’ questions
4.2.2.2 Analysis of the qualitative data (free-text answers) 4.2.3 Supplementary qualitative analysis of parent interviews 4.2.3.1 Thematic analysis
4.2.3.2 Comparison of fathers’ and mothers' responses
4.2.4 Case study narratives based on free-text answers from the parent questionnaires and interview material
For the purpose of clarity, each of the above topics will be re-presented below and followed by its relevant research question as well as analysis and results.
4.2.1 Session analysis: Main effects and interactions
The analysis of target behaviors (dependent variables) was carried out in order to answer the following questions:
Primary question:
Does music therapy enhance spontaneous communicative interactions of young children, following cochlear implantation?
Sub-question:
Among these children, is the frequency and/or duration of spontaneous communicative interactions significantly greater in undirected42 or directed music and play experiences?
The independent variables were:
1) Condition: music therapy vs. play 2) Session part: directed vs. undirected 3) Interaction of condition with session part
The dependent variables were analyzed by using the complete video recordings, for all five children (75 sessions of 20 minutes each; see section 3.9.2). The analysis included frequency data of all four variables (initiation, imitation, synchronization and turn-taking), duration for synchronization and turn–taking, and number of events of turn–taking.
In order to answer the primary question and its sub-question, all the dependent variables were analyzed according to seven questions formulated and presented in section 3.9.2. Each of these questions, which examine differences in frequency and/or duration, includes six comparisons between the two conditions, music therapy and
42 The undirected and directed approaches are explained in the Method chapter, section 3.7.
play. These comparisons are presented in Table 3.6.
All dependent variables involving counts and frequencies of events were analyzed by a Generalized Linear Mixed Model (GLMM). This analysis is analogous to the more traditional repeated measures Analysis of Variance (ANOVA), but allows for greater flexibility in dealing with various forms of distribution of data. Count and frequency data typically follow a Poisson distribution (Upton & Cook, 2002). Such distributions can be modeled with GLMMs, but not with traditional ANOVAs. In this study, GLMMs were fitted using Penalized Quasi-Likelihood (R Version 2.1.0, R Development Core Team, 2005; function glmmPQL in R package MASS, Venables
& Ripley, 2002).
As a sensitivity analysis, the researcher also calculated ANOVAs of more traditional Linear Mixed-Effects Models, based on a normal distribution (function lmer in R package lme4). The use of these models would not have altered the conclusions. Therefore, only the glmmPQL models using the more appropriate Poisson distribution were retained and are presented here.
Inferential statistical analysis was undertaken on the frequency and/or duration data points collected during the video analysis for each variable, from each of the subjects (75 sessions of 20 minutes each). Due to the small number of subjects, test power was relatively low, although the use of multiple measurements in each subject may partly compensate for this. A power calculation was not carried out because the main focus of the study was on observing the individual subjects' spontaneous communicative interactions. The low test power implies that inferential statistics may yield non-significant results even if the therapy was effective. Significant results, however, are valid with the nominal significance level. Because of the low test power, particular emphasis was placed on descriptive analysis, as opposed to relying strongly on the interpretation of p-values.
All analyses and significant effects will be now presented in detail. The values presented in the text all follow the publication manual of the American Psychological Association (2001) requirements of a maximum value to three decimal points (.001), but there are several examples where a much higher significance level was reported in the analyses. The reader may refer to Appendix X for the actual p-values.
4.2.1.1 Frequency of spontaneous imitation
The first analysis reports the differences in frequency of spontaneous imitation when comparing the music therapy condition and the play condition (six different indicates that the frequency of spontaneous imitation is significantly greater in the music therapy condition than in the play condition.
There was no significant main effect for the independent variable session part, nor was there any significant interaction between condition and session part.
Figure 4.1 depicts these results in a boxplot. Boxplots can be used for the comparison of several samples, and will depict all the followed significant results of the dependent variables; therefore, a detailed explanation of a boxplot will be now presented.
The boxplot (box-whisker diagram), is a graphic representation of numerical data, without any assumptions of statistical distribution. In descriptive statistics, a boxplot represents the five-number summary, which consists of the smallest observation, lower quartile, the median value, upper quartile, and the largest observation. The x-axis represents independent variables (either music therapy vs.
play, or undirected session part vs. directed session part). The y-axis represents the scoring ranges of the dependent variables (either frequency or duration data). Every rectangular box represents the results of the first to the third quartile (i.e. 25 to 75 percentile) which is the inter-quartile range (IQR); thus, the area in the box represents the middle 50% of the scoring range. The bold line inside the box indicates the
median value. Vertical tic marks, or ‘whiskers’, are then drawn extending above and below the box to the greatest and least observed values. The whiskers extend, at most, to 1.5 times the inter-quartile range. Any values beyond the ends of the whiskers are shown individually as outliers and are indicated by the presence of open dots. In other words, an outlier is a data point which lays more than 1.5 times IQR lower than the first quartile, or 1.5 times IQR higher than the third quartile (Everitt, 1996, pp. 30-32;
Upton & Cook, 2002, p. 47).
Play Music therapy
01020304050
Condition
Frequency of Spontaneous Imitation
Figure 4.1. Frequency of spontaneous imitation by condition
This boxplot (Figure 4.1) shows that the area of music therapy is greater than that of the play condition. From the dimensions of the music therapy box, one can see that its lower border is approximately at the same height as the upper box line for play. In addition, the median value is higher and the whiskers extend further in music therapy than in play. This result suggests that music therapy yielded a much greater incidence of spontaneous imitations than play.
4.2.1.2 Frequency of spontaneous initiation
Table 4.4 presents the results of a repeated measures ANOVA for frequency of spontaneous initiation and shows a significant effect (p < .001) of the condition variable. This indicates that the frequency of spontaneous initiation is significantly greater in the music therapy condition than in the play condition.
No significant effect was found for the independent variable session part (p = .06); however, the result may have reached significance, with a larger sample.
No significant effect was found for the interaction of condition with session part.
Figure 4.2 depicts the results in a boxplot.
Table 4.4. ANOVA table for the GLMM of frequency of spontaneous initiation
Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value
p-value
Condition 1 141 74.65 ***
Session part 1 141 3.55 0.06
Condition x Session part 1 141 1..84 0.18
***p < .001
Play Music therapy
102030405060
COndition
Frequency of Spontaneous Initiation
Figure 4.2. Frequency of spontaneous initiation by condition
Viewing the plot for spontaneous initiation (Figure 4.2), one can see that the lower border of the music therapy box is approximately at the same height as the play’s upper box line. In addition, the music therapy area box is greater, the median value is higher, and the whiskers extend further than for play. This boxplot documents the greater frequency of spontaneous initiation in the music therapy sessions than in the play sessions.
4.2.1.3 Frequency of spontaneous turn-taking
Table 4.5 presents the results of a repeated measures ANOVA on differences in frequency of spontaneous turn-taking when comparing music therapy and play.
Table 4.5. ANOVA table for the GLMM of frequency of spontaneous turn-taking
***p < .001
A significant effect (p < .001) was found for the variable condition. This result indicates that the frequency of spontaneous turn-taking is significantly greater in music therapy than in play.
A significant effect (p < .05) was also found for the variable session part. This result indicates that spontaneous turn-taking occurred more frequently in the undirected part of both the music therapy and the play sessions, than in the directed part.
No interaction effect was found for condition with session part.
Figures 4.3 and 4.4 depict these results in boxplots.
Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value p-value
Condition 1 141 45.95 ***
Session part 1 141 6.49 0.01
Condition x Session part 1 141 2.67 0.10
Play Music therapy
02468101214
Condition
Frequency of Spontaneous Turn-taking
Figure 4.3. Frequency of spontaneous turn-taking by condition
As with the previous two communicative interactions, the boxplot for spontaneous turn-taking (Figure 4.3) shows a noticeable difference between the music therapy and the play conditions confirming that spontaneous turn-taking occurred much more frequently in the music therapy than in the play condition.
undirected directed
02468101214
Session Part
Frequency of Spontaneous Turn-taking
Figure 4.4. Frequency of spontaneous turn-taking by session part
Although the lower border and median value for the undirected and directed session parts (Figure 4.4) are essentially the same, the much larger area of the
undirected box supports the conclusion that spontaneous turn-taking occurred much more frequently during the undirected part of the session than during the directed part for both the music therapy and play conditions.
4.2.1.4 Frequency of spontaneous synchronization
Table 4.6 presents the results of a repeated measures ANOVA on differences in frequency of spontaneous synchronization when comparing music therapy and play.
Table 4.6. ANOVA table for the GLMM of frequency of spontaneous synchronization
Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value p-value
Condition 1 141 49.08 ***
Session part 1 141 1.54 0.21
Condition: Session part 1 141 0.36 0.54
***p < .001
Table 4.6 presents the results of a repeated measures ANOVA on differences in frequency of spontaneous synchronization when comparing music therapy and play.
There is a significant effect (p < .001) of the condition variable, which indicates that the frequency of spontaneous synchronization is significantly greater in the music therapy than in the play condition. No significant effect was found for the independent variable session part or for the interaction of condition with session part.
Figure 4.5 depicts the results in a boxplot.
Play Music therapy
02468
Condition
Frequency of Spontaneous Synchronization
Figure 4.5. Frequency of spontaneous synchronization by condition
The boxplot for spontaneous synchronization (Figure 4.5) shows a marked difference between the music therapy condition and the play condition. As with spontaneous turn-taking, the median value in play is zero, while its value in music therapy is higher. Also, the box size and the extent of the whiskers are far greater in music therapy than in play. This result suggests that spontaneous synchronization occurred much more frequently in the music therapy than in the play condition.
4.2.1.5 Duration of spontaneous synchronization
Table 4.7 presents the results of a repeated measures ANOVA on differences in duration of spontaneous synchronization when comparing music therapy and play.
Table 4.7. ANOVA table for the GLMM of duration of spontaneous synchronization
***p < .001 Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value
p-value
Condition 1 141 36.02 ***
Session part 1 141 1.01 0.32
Condition x Session part 1 141 0.16 0.69
There is a significant effect (p < .001) of the condition variable, which indicates, as with frequency of spontaneous synchronization, that the duration of spontaneous synchronization was significantly longer in the music therapy than in the play condition.
No significant effect was found for session part or for the interaction of condition with session part.
Figure 4.6 depicts the results in a boxplot.
Play Music therapy
010203040
Condition
Duration of Spontaneous Synchronization
Figure 4.6. Duration of spontaneous synchronization by condition
The boxplot (Figure 4.6) shows a marked difference between the music therapy and play conditions for this variable, which means that music therapy was much more effective in facilitating longer duration of spontaneous synchronization than play.
4.2.1.6 Duration of spontaneous turn-taking
Table 4.8 presents the results of a repeated measures ANOVA on differences in duration of spontaneous turn-taking when comparing music therapy and play.
Table 4.8. ANOVA table for the GLMM of duration of spontaneous turn- taking
***p < .001
A significant effect (p < .001) was found for the condition variable, which indicates that there were significantly longer durations of spontaneous turn-taking in music therapy than in the play condition.
A significant effect was also found for the variable session part (p = .001), which indicates that in the undirected part of the session (in music therapy and in play), there were longer durations of spontaneous turn-taking. No interaction effect was found for condition with session part.
Figures 4.7 and 4.8 depict the results in boxplots.
Play Music therapy
050100150200
Condition
Duration of Spontaneous Turn-taking
Figure 4.7. Duration of spontaneous turn-taking by condition
The above boxplot (Figure 4.7) illustrates that the box area of the music therapy condition is much greater than the box for play. In addition, the median value and the
Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value
p-value
Condition 1 141 35.50 ***
Session part 1 141 11.55 0.001
Condition x Session part 1 141 0.05 0.82
extent of the whiskers also indicate that music therapy was much more effective in facilitating longer durations of spontaneous turn-taking than play.
undirected directed
050100150200
Session Part
Duration of Spontaneous Turn-taking
Figure 4.8. Duration of spontaneous turn-taking by session part
The boxplot (Figure 4.8) illustrates that the box area of undirected session part is much greater than the box of the directed session part for spontaneous turn-taking.
Although the two boxes start from the value of zero and the median has almost the same value, the box size and the extent of the whiskers indicate that the undirected session part (in music therapy and play) was much more effective in facilitating longer durations of spontaneous turn-taking than the directed part.
4.2.1.7 Number of events of spontaneous turn-taking
Table 4.9 presents the results of a repeated measures ANOVA on differences in the number of events of spontaneous turn-taking when comparing music therapy and play.
Table 4.9. ANOVA table for the GLMM of number of events of spontaneous turn-taking
***p < .001
There is a significant effect (p < .001) of the condition variable, which indicates that the number of events of spontaneous turn-taking was significantly greater in the music therapy than in play.
A significant effect (p = .01) of session part variable indicates that in the undirected part of the session (in music therapy and in play), there were more events of spontaneous turn-taking. No interaction effect was found for condition with session part.
Figure 4.9 and 4.10 depict the results in boxplots.
Play Music therapy
05101520253035
Condition
Number of Events of Spontaneous Turn-taking
Figure 4.9. Number of events of spontaneous turn-taking by condition The above boxplot (Figure 4.9) illustrates that the box area of the music therapy condition is much greater than the box of the play condition. The median value and Variable
Numerator Degrees of Freedom
Denominator Degrees of
Freedom
F-value p-value
Condition 1 141 30.45 ***
Session part 1 141 7.30 0.01
Condition x Session part 1 141 0.52 0.47
the extent of the whiskers also indicate that music therapy was much more effective in facilitating many more events of spontaneous turn-taking than play.
undirected directed
05101520253035
Session Part
Number of Events of Spontaneous Turn-taking
Figure 4.10. Number of events of spontaneous turn-taking by session part The boxplot (Figure 4.10) illustrates that the box area of undirected session part is much greater than the box of the directed part. Despite the fact that the two boxes start from the value of zero and the median in both boxes are similar, the box size and the extension of the whiskers indicate that the undirected session part for both music therapy and play was more effective in facilitating more events of spontaneous turn-taking than the directed part.
In summary, statistical analysis revealed a significant main effect (p < .001) for condition for all seven dependent variables. There was a significant main effect for session part for frequency of spontaneous taking (p < .05), duration of turn-taking (p < .001), and number of events of turn-turn-taking (p < .01), all favoring the undirected part of the session. There was no significant interaction of condition with session part for any of the variables.