Strengths and limitations

5.6.1. Change in maternal perception of outcome measures

There were several limitations to the current study. It must be noted that whilst the responsive parenting program is child focused, there was no information directly collected from the child. The variables in this study were measured by self-report questionnaires completed by the mother with no objective verification, and therefore any changes remain perceived changes. Whilst most of the measures had good psychometric properties it was not possible to estimate or prevent response bias. Furthermore, the measures of sleep,

particularly child sleep, may not have offered sufficient specificity to allow for significant change to be detected. Therefore, it has not been established whether there were actual improvements in the bonding between the mother and her child, the child’s temperament, the mother’s competence, or amount of sleep for mother and baby. Objective observations would be required to establish actual improvements in these areas.

5.6.2. Randomization and a control group.

An obvious limitation to the study was the lack of randomization and control. The absence of these factors limited the attribution of causation in the study. However, given the statistically significant results, this study has provided strong evidence that future research replicating the study with randomization of participants to a treatment and a control group is warranted. The inclusion of a control group would allow for the attribution of causality by eliminating the possibility that results were due to maturation, or regression to the mean.

5.6.3. Response bias.

There were few significant characteristic differences between those in the retained samples and those lost to follow up. Differences observed included the subsample who returned data at all three time points being more likely to be breastfeeding their child at pre- program attendance, and those who returned data pre and post-program being more likely to have more than one child, and also to have a history of mental health problems than those who dropped out of the study. This suggests that response bias due to characteristic differences between the retained subsamples and the original sample were minimized.

However, the identification during data analysis of the participant who reported extremely low pre-program attendance levels of perceived mother-child bonding combined with high depressive symptoms, and endorsement of the self-harm item on the mood measure, provided a unique opportunity to compare these responses with the participant’s admission screening responses on the same mood measure. When that participant’s responses to the same mood measure at program admission were examined by staff at Tweddle they reported a different pattern of results. This raised the question of whether the participant was prone to socially desirable responding when completing the screening questionnaires at the time of admission. An alternate explanation may be that as the

screening measure was completed at admission, that simply attending the program may have brought a sense of relief and hope to the participant that they would receive the help that they were seeking, which may have resulted in them reporting less symptoms at that time.

5.6.4. Selection bias.

Whilst it has been established with some degree of certainty that the retained sample did not differ significantly from those lost to follow up on the outcome measures, there remains a possibility of the presence of selection bias as the participants in this study elected

whether or not they would participate. Of particular note in the current sample was the comparatively high level of tertiary educated participants. This may be a reflection of those with higher education being more likely to ask for help. Alternatively, those with a high level of education may also be more likely to volunteer for the study. This suggests that the current sample may not be representative of all program attendees.

However, the proportion of participants with a post-secondary school education in the current sample was comparable with the study sample used in research conducted on a previous residential program conducted at Tweddle in 2002 (Rowe & Fisher, 2010). In that study, 62 per cent of those who received questionnaires completed and returned them. This represented over 50 per cent of all eligible program attendees during the data collection period which is a significant proportion of the available participants. This suggests that it is more likely that the overrepresentation of tertiary educated mothers in the current sample reflects a higher rate of help-seeking behaviour and therefore attendance at a parenting program, rather than a higher likelihood of volunteering to participate in the study.

5.6.5. Attrition rates.

One obvious limitation to the current study was the extremely low response rate which was then further eroded by a high attrition rate. This resulted in a small sample size. Despite adequate power being attained for the analyses to proceed and to obtain statistically significant results, the small sample size limited the opportunity to control for covariates other than differences in maternal mood.

When compared to other studies with similar methodologies such as Fisher et al., (2002), and Rowe & Fisher (2010), there appears to be one difference which may explain the low initial response rate. In those studies attendees received a verbal explanation of the study at admission to the program, and then the questionnaires were hand delivered by the

researcher. Meeting the researcher in person during recruitment may have had a beneficial effect by evoking a sense of loyalty in the mother. Furthermore, receiving the research information that way may have given the study more credibility, and further, evoked a sense of obligation to participate in the study. If this was the case, this obligation may have increased the likelihood of the participant completing the post-program and follow up measures also. This may particularly be the case in the Rowe and Fisher (2010) study as the researchers also contacted the participant by telephone one month after attendance to receive consent to send the post-program questionnaire. Contact was again made for the follow up questionnaire six months post attendance.

Furthermore, as the participants were attending the program because they were experiencing some sort of stress or fatigue due to the busy job of caring for an infant, they may have lacked the time and energy to complete the questionnaire at home. Despite the conscious effort made to design the questionnaire so that most responses could just be circled, making it as quick and easy to complete as possible, the task may have felt overwhelming fatigued mothers. It is possible that attendees had more available time to complete the questionnaires at the program, due to being away from their normal home duties.

Mothers may have been more motivated to participate in the study if some type of incentive had been offered. The opportunity to receive a gift voucher for participation is often used in research, however, in an effort to avoid coercing mothers to participate this type of incentive was not offered.

5.6.6. Effect sizes.

A strength of the current study was the magnitude of the observed effect sizes. Despite the small sample size the observed differences in scores yielded large effect sizes

which ultimately provided enough power in the analyses to allow for the detection of significant results. This is sound evidence that the variables in the study were appropriately included and warrant further exploration in future studies.

5.6.7. Maternal mood.

One limitation in the current study was a potential floor effect in the maternal mood measure. Whilst it is a widely validated and reliable screening tool, the Edinburgh Postnatal Depression Scale (EPDS; Cox et al., 1987) was limited in its ability to detect small changes in mood once participant’s scores had decreased from the clinical range (>12) to the normal range. This may have resulted in an inability to detect statistically significant improvements from post-program to follow up data collection. If floor effects were present in the current study this may have affected the interpretation of the results.

5.6.8. Child sleep.

As discussed in detail above (5.4.5.), the scale used to measure the amount of child sleep, may have limited the item’s ability to detect statistically significant improvements in this variable. With few options available at the upper end of the scale item, it is probable that ceiling effects reduced the likelihood of obtaining meaningful results with this measure.