Application of Repeated-Measures Analysis of Variance and Hierarchical Linear Model in Nursing Research

The one-way ANOVA test explained

BACKGROUND

Quantitative methods and statistical analysis are essential tools in nursing research, as they support researchers testing phenomena, illustrate their findings clearly and accurately, and provide explanation or generalisation of the phenomenon being investigated. The most popular inferential statistics test is the one-way analysis of variance (ANOVA), as it is the test designated for comparing the means of a study's target groups to identify if they are statistically different to the others. However, the nursing literature has identified that statistical tests are not being used correctly and findings are being reported incorrectly.

AIM

To present and explain the one-way ANOVA.

DISCUSSION

The article presents the purpose of inferential statistics and explains one-way ANOVA. It uses relevant examples to examine the steps needed to successfully apply the one-way ANOVA. The authors also provide recommendations for other statistical tests and measurements in parallel to one-way ANOVA.

CONCLUSION

Nurses need to develop their understanding and knowledge of statistical methods, to engage in research and evidence-based practice.

IMPLICATIONS FOR PRACTICE

This article enhances the understanding and application of one-way ANOVAs by nursing students, novice researchers, nurses and those engaged in academic studies. Nurses, nursing students and nurse researchers need to familiarise themselves with statistical terminology and develop their understanding of statistical concepts, to support evidence-based, quality, safe care.

Longitudinal trajectories of illness perception regarding breast cancer-related lymphedema among women with breast cancer

OBJECTIVE

To identify longitudinal trajectories of illness perception (IP) regarding breast cancer-related lymphedema (BCRL) in the first six months after surgery among women with breast cancer and to explore the predictive effects of demographics and clinical factors on IP trajectories.

METHODS

From August 2019 to August 2021, a total of 352 patients participated in this study, 328 of whom were included in the data analysis. Demographic and clinical characteristics were collected at baseline (1-3 days after surgery). The BCRL-specific revised illness perception questionnaire was used to measure IP regarding BCRL at baseline and 1 month, 3 months and 6 months post-surgery. A multilevel model was conducted to analyze the data.

RESULTS

Over the first six months post-surgery, the "timeline acute/chronic" and "illness coherence" dimensions showed positive growth trajectories; the "personal control" and "treatment control" dimensions presented negative growth trajectories; and the trajectories of identity, consequences, cyclicality and emotional influence perceptions regarding BCRL showed no significant changes. Age, education level, marital status, employment status, family monthly income per person, cancer stage and status of removed lymph nodes were indicated to be predictive factors of IP trajectories.

CONCLUSIONS

The present study determined significant changes over the first six months post-surgery in four IP dimensions and predictive effects of some demographics and clinical details on IP trajectories. These findings may help healthcare providers know more about the dynamic characteristics of IPs regarding BCRL in patients with breast cancer and assist them in identifying patients with a tendency toward improper IP regarding BCRL.

Baseline cognitive functioning can predict the trajectory of acute treatment in first-episode major depressive disorder

OBJECTIVE

This study aims to investigate the role of cognitive function in the efficacy prediction of selective serotonin reuptake inhibitors (SSRIs) for depression patients and to further the understanding of the relationship between baseline cognitive function and depression trajectory.

METHODS

This was part of a multicenter study for major depressive disorder. The study included 172 first-episode depression patients and 93 recurrent depression patients who had their cognitive function assessed at baseline and followed up for 8 weeks of SSRI treatment.

RESULTS

After constructing a 2-level hierarchical linear model with depression change- and cognitive function-level variables, the processing speed at baseline was the best predictor for the improvement of depression at each follow-up in first-episode patients (G11 = 0.03, P = 0.042). The treatment prediction model slope varied across patients depending on the processing speed scores at baseline. With the receiver operating characteristic curve, the combination of sociodemographic characteristics, sedative hypnotics, baseline 17-item Hamilton Rating Scale for Depression (HAMD₁₇), and cognitive function showed the highest predictive power in major depressive disorder remission, resulting in a classification accuracy of 71.5%, a sensitivity of 82.5%, and a specificity of 55.1% (AUC = 0.713; P < 0.001).

CONCLUSION

Baseline cognitive function could help clinicians to better understand the trajectory of first-episode depression patients during acute treatment with SSRIs.

Testing mediational processes of substance use relapse among youth who participated in a mobile texting aftercare project

BACKGROUND

The goal of this paper is to advance the understanding of mechanisms of action involved in behavioral-driven aftercare interventions for substance use disorders (SUDs) among youth populations. This paper reports data from a study that measured the impact of an aftercare intervention on primary substance use relapse among youth who completed treatment in Los Angeles County for SUDs. The aftercare intervention, Project ESQYIR-Educating and Supporting inQuisitive Youth In Recovery, utilized text messaging to monitor relapse and recovery processes, provide feedback, reminders, support, and education among youth from SUD specialty settings during the initial 3-month period following treatment completion.

Method: Mediational modeling informed by Baron and Kenny was used to examine the extent to which select recovery processes including participation in extracurricular activities and self-help, were impacted by the texting intervention, and if such processes helped sustain recovery and prevent primary substance use relapse. The data come from a two-group randomized controlled pilot study testing the initial efficacy of a mobile health texting aftercare intervention among 80 youth (M_age= 20.7, SD = 3.5, range: 14-26 years) who volunteered to participate after completing SUD treatment between 2012 and 2013.

Results: Among the two recovery processes examined in the mediational modeling, only involvement in extracurricular activities mediated the effects of the texting aftercare intervention on reductions in primary substance use relapse; not self-help participation.

Conclusion: Findings from this pilot study offer greater understanding about potential recovery-related mechanisms of action of mobile aftercare interventions. Mobile texting was found to promote increased engagement in recovery-related behaviors such as participation in extracurricular activities, which mediated the effects of the mobile aftercare intervention on decreasing primary substance use relapse. Findings suggest mobile approaches may be effective for increasing adherence to a wide-array of recovery behavioral regiments among youth populations challenged by complex behavioral issues.

The Impact of COVID-19-Related Restrictions on Social and Daily Activities of Parents, People With Disabilities, and Older Adults: Protocol for a Longitudinal, Mixed Methods Study

BACKGROUND

The COVID-19 pandemic has led to wide-scale changes in societal organization. This has dramatically altered people's daily activities, especially among families with young children, those living with disabilities such as spinal cord injury (SCI), those who have experienced a stroke, and older adults.

OBJECTIVE

We aim to (1) investigate how COVID-19 restrictions influence daily activities, (2) track the psychosocial effects of these restrictions over time, and (3) identify strategies to mitigate the potential negative effects of these restrictions.

METHODS

This is a longitudinal, concurrent, mixed methods study being conducted in British Columbia (BC), Canada. Data collection occurred at four time points, between April 2020 and February 2021. The first three data collection time points occurred within phases 1 to 3 of the Province of BC's Restart Plan. The final data collection coincided with the initial distribution of the COVID-19 vaccines. At each time point, data regarding participants' sociodemographics, depressive and anxiety symptoms, resilience, boredom, social support, instrumental activities of daily living, and social media and technology use were collected in an online survey. These data supplemented qualitative videoconference interviews exploring participants' COVID-19-related experiences. Participants were also asked to upload photos representing their experience during the restriction period, which facilitated discussion during the final interview. Five groups of participants were recruited: (1) families with children under the age of 18 years, (2) adults with an SCI, (3) adults who experienced a stroke, (4) adults with other types of disabilities, and (5) older adults (>64 years of age) with no self-reported disability. The number of participants we could recruit from each group was limited, which may impact the validity of some subgroup analyses.

RESULTS

This study was approved by the University of British Columbia Behavioural Research Ethics Board (Approval No. H20-01109) on April 17, 2020. A total of 81 participants were enrolled in this study and data are being analyzed. Data analyses are expected to be completed in fall 2021; submission of multiple papers for publication is expected by winter 2021.

CONCLUSIONS

Findings from our study will inform the development and recommendations of a new resource guide for the post-COVID-19 period and for future public health emergencies.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/28337.

Pilot randomized clinical trial targeting anxiety sensitivity: effects on physical activity

Anxiety sensitivity (AS)-the tendency to interpret anxiety as an aversive state-is associated with low rates of physical activity. Previous interventions targeting AS via exercise-based interoceptive exposure have not assessed physical activity as an outcome and are limited by brief follow-up periods. This study replicated and extended previous work by including a 6-week follow-up and assessing physical activity. Participants were 44 sedentary young adults with elevated AS randomized to intervention (six 20-minute sessions of moderate-intensity walking) or assessment-only control. Assessments of AS and physical activity were conducted at baseline and weeks 2 (post-treatment), 4, and 8. Between-group change in AS and physical activity over time was assessed using hierarchical linear modeling. The intervention condition demonstrated a marginally significant reduction in AS compared to control at week 4, which eroded by week 8. There were no significant between-group differences for change in physical activity. Findings indicate that a brief intervention might not be sufficient to produce lasting changes in AS or related exercise avoidance without additional treatment. Intervention effects were weaker than previous reports, which may be due to the greater racial/ethnic diversity of the current sample. Future research should objectively measure physical activity and explore individual variability in response.ClinicalTrials.gov identifier: NCT03128437.

Coordination Cost and Super-Efficiency in Teamwork: The Role of Communication, Psychological States, Cardiovascular Responses, and Brain Rhythms

To advance knowledge on the psychophysiological markers of "coordination cost" in team settings, we explored differences in meta-communication patterns (i.e., silence, speaking, listening, and overlap), perceived psychological states (i.e., core affect, attention, efficacy beliefs), heart rate variability (i.e., RMSSD), and brain rhythms (i.e., alpha, beta and theta absolute power) across three studies involving 48 male dyads (Mage = 21.30; SD = 2.03). Skilled participants cooperatively played three consecutive FIFA-17 (Xbox) games in a dyad against the computer, or competed against the computer in a solo condition and a dyad condition. We observed that playing in a team, in contrast to playing alone, was associated with higher alpha peak and global efficiency in the brain and, at the same time, led to an increase in focused attention as evidenced by participants' higher theta activity in the frontal lobe. Moreover, we observed that overtime participants' brain dynamics moved towards a state of "neural-efficiency", characterized by increased theta and beta activity in the frontal lobe, and high alpha activity across the whole brain. Our findings advance the literature by demonstrating that (1) the notion of coordination cost can be captured at the neural level in the initial stages of team development; (2) by decreasing the costs of switching between tasks, teamwork increases both individuals' attentional focus and global neural efficiency; and (3) communication dynamics become more proficient and individuals' brain patterns change towards neural efficiency over time, likely due to team learning and decreases in intra-team conflict.

Development of Chinese Junior High School Students' Creative Potential: Within-Person and Between-Person Effects of Student-Student Support and Need for Cognition

A longitudinal study was conducted to examine the developmental trend of creative potential in Chinese junior high school students and the within-person and between-person effects of student–student support and need for cognition. Two hundred and fourteen Chinese junior high school students participated in the present study (mean age = 13.29 years, SD = 0.49 years, 116 boys). Student–student support, need for cognition, and creative potential were measured once per year for 3 years. Longitudinal multilevel models indicated that (1) Chinese junior high school students’ creative potential showed a downward trend from grades 7 to 9; (2) at the within-person level, time-varying student–student support positively predicted time-varying creative potential; (3) at the within-person level, time-varying need for cognition moderated the positive link between time-varying student–student support and time-varying creative potential; and (4) at the between-person level, no support was found for the links between student–student support, need for cognition, and creative potential. Specifically, average levels of student–student support neither significantly predicted initial levels and developmental rates of creative potential nor moderated the links between average levels of student–student and initial levels and developmental rates of creative potential. The findings highlight that at the within-person and between-person levels, student–student support and need for cognition have differential influences on Chinese junior school students’ creative potential.

The Preliminary Efficacy of a Technology-Based Cancer Pain Management Program Among Asian American Breast Cancer Survivors

With few existing technology-based programs to support cancer pain management, the need for culturally tailored programs to support ethnic minority cancer survivors has been highlighted. The purpose of this study was to explore the preliminary efficacy of the technology-based CAncer Pain management support Program for Asian American survivors of breast cancer, a technology-based cancer pain management program, in improving the cancer pain experience of Asian American breast cancer survivors. This pilot study adopted a randomized repeated-measures pretest/posttest control group design with a sample of 94 Asian American breast cancer survivors. Study measures included the Brief Pain Inventory-Short Form, Support Care Needs Survey-34 Short Form, and Mishel Uncertainty in Illness Scale-Community. Data were analyzed using descriptive and inferential statistics including repeated-measures analysis of covariance. Although there were no significant differences in pain, there were significant changes in perceived isolation (F = 9.937, P < .01), personal resources (F = 6.612, P < .05), support care need (F = 8.299, P < .01), and degree of uncertainty (F = 8.722, P < .01) in the intervention group from pretest to posttest. These findings support the positive effects of CAncer Pain management support Program for Asian American survivors of breast cancer on the cancer pain experience of Asian American breast cancer survivors.

Investigation of Longitudinal Data Analysis: Hierarchical Linear Model and Latent Growth Model Using a Longitudinal Nursing Home Dataset

The appropriate use of the data analysis method in a longitudinal design remains controversial in gerontological nursing research. The objective of the current study is to compare statistical approaches between a hierarchical-linear model (HLM) and a latent-growth model (LGM) in random effects, variance explained, growth trajectory, and model fitness. Secondary analysis of longitudinal data was used. Two variables were chosen to demonstrate the comparison between statistical methods. The HLM was superior in addressing unbalanced data in repeated-measures analysis of variance (ANOVA) and multivariate ANOVA because its nested data structure and random effects could be estimated. The LGM had advantages in modeling growth trajectories and model-fit comparisons. Superior to the HLM, the LGM reported more acceptable data fit, reporting a quadratic model, and successfully differentiated between and within components. The current research provides some evidence for applying appropriate statistical methods when addressing longitudinal datasets in gerontological nursing research. [Research in Gerontological Nursing, 12(6), 275-283.].

Effects of differences in wiping pressure applied by nurses during daily bed baths on skin barrier function, cleanliness, and subjective evaluations

AIM

To clarify the actual condition and examine the effects of differences in wiping pressure applied by clinical nurses during daily bed baths on skin barrier function, cleanliness, and subjective evaluations.

METHODS

For the purposes of the present quasi-experimental interventional study, "wiping pressure" was defined as the "force applied vertically to the skin surface during bed baths." Two types of bed baths, one using ordinary wiping (pressure: 23-25 mmHg) and the other using weak wiping (pressure: 12-14 mmHg), were performed on the forearms (right and left) of 30 healthy adult men and women, and the effects on transepidermal water loss, stratum corneum hydration, cleanliness, and subjective evaluations were examined.

RESULTS

The results showed no differences between ordinary and weak wiping pressure in regard to the effects on skin barrier function and cleanliness. In terms of subjective evaluations, a significant association was seen between wiping pressure and the "sensation of having dirt removed" (P = .036). Regarding "degree of pain," some participants reported that the wiping pressure felt "slightly painful" under both conditions (ordinary: 31.1%; weak: 10.7%), while some with sensitive skin reported feeling pain even during weak wiping pressure.

CONCLUSIONS

The results of the present study suggest that skin assessments should be performed before and after bed baths, and that wiping pressure should be controlled and evaluated while considering the patient's feelings.

Effects of a mind map-based life review programme on psychospiritual well-being in cancer patients undergoing chemotherapy: A randomised controlled trial

OBJECTIVES

To evaluate the effects of a mind map-based life review programme (MBLRP) on psychological distress, hope, meaning in life and self-transcendence in cancer patients undergoing chemotherapy.

METHODS

Eighty-four cancer patients undergoing chemotherapy from a university-affiliated hospital in Fujian, China. The participants were randomly allocated to a MBLRP group (n = 40) or usual care group (n = 44). Data were collected at baseline (T0), on the second day (T1) and four weeks after the programme (T2) using the Distress Thermometer, Meaning in Life Questionnaire, Herth Hope Scale and Self-transcendence Scale.

RESULTS

No significant interaction effects for time and group membership were found for psychological distress either at T1 (t = -1.707, p = .090) or at T2 (t = -1.123, p = .263). The interaction effects for T1 and group membership were statistically significant for meaning in life (t = 3.487, p = .001) and hope (t = 5.313, p < .001), but not statistically significant for self-transcendence (t = 0.148, p = .882). The interaction effects for T2 and group membership were statistically significant for meaning in life (t = 2.592, p = .01), hope (t = 5.215, p < .001) and self-transcendence (t = 2.843, p = .005).

CONCLUSIONS

The MBLRP could improve hope, meaning in life and self-transcendence in cancer patients undergoing chemotherapy.

Application of a Frailty Modeling Approach to Correlated Breastfeeding Duration Data

BACKGROUND

Correlated breastfeeding duration data are very common in infant feeding research using cohort designs. Intracluster correlation within the same clustering group is expected and needs to be taken into account in statistical analysis; otherwise, the corresponding statistical inferences may be subject to an increased Type I error.

OBJECTIVES

The aims of this study were to illustrate the necessity of adjusting for the intracluster correlation in correlated breastfeeding duration data analysis and to demonstrate different frailty modeling approaches.

METHODS

An introduction to shared frailty models was presented under the assumption of proportional hazards (PH). Then, two different approaches-the Cox frailty model (semiparametric approach) and the parametric frailty model (parametric approach)-were used to fit the data from a maternal cohort in Nepal as an illustrative example.

RESULTS

For the semiparametric approach, random effects denoting the variations in the hazard of breastfeeding cessation shared by mothers living in the 27 distinct communities were estimated and graphically presented. Compared with the conventional Cox model, Cox frailty model reduced the chance of Type I error occurring, providing a better model fit in the presence of correlated survival data. Among candidate parametric approaches, a Weibull PH model with a gamma frailty term was selected as an appropriate model fitting the breastfeeding data.

DISCUSSION

Shared frailty models can be used in other research areas in the presence of correlated time-to-event data. Model selection depends on the assumption of PH, the specification of the baseline hazard function, and also the study purpose.

Recommendations for analysis of repeated-measures designs: testing and correcting for sphericity and use of manova and mixed model analysis

PURPOSE

A common experimental design in ophthalmic research is the repeated-measures design in which at least one variable is a within-subject factor. This design is vulnerable to lack of 'sphericity' which assumes that the variances of the differences among all possible pairs of within-subject means are equal. Traditionally, this design has been analysed using a repeated-measures analysis of variance (RM-anova) but increasingly more complex methods such as multivariate anova (manova) and mixed model analysis (MMA) are being used. This article surveys current practice in the analysis of designs incorporating different factors in research articles published in three optometric journals, namely Ophthalmic and Physiological Optics (OPO), Optometry and Vision Science (OVS), and Clinical and Experimental Optometry (CXO), and provides advice to authors regarding the analysis of repeated-measures designs.

RECENT FINDINGS

Of the total sample of articles, 66% used a repeated-measures design. Of those articles using a repeated-measures design, 59% and 8% analysed the data using RM-anova or manova respectively and 33% used MMA. The use of MMA relative to RM-anova has increased significantly since 2009/10. A further search using terms to select those papers testing and correcting for sphericity ('Mauchly's test', 'Greenhouse-Geisser', 'Huynh and Feld') identified 66 articles, 62% of which were published from 2012 to the present.

SUMMARY

If the design is balanced without missing data then manova should be used rather than RM-anova as it gives better protection against lack of sphericity. If the design is unbalanced or with missing data then MMA is the method of choice. However, MMA is a more complex analysis and can be difficult to set up and run, and care should be taken first, to define appropriate models to be tested and second, to ensure that sample sizes are adequate.

Challenges of evaluating a computer-based educational programme for women diagnosed with early-stage breast cancer: a randomised controlled trial

In a two-group, multi-centre, randomised controlled 9 months trial, we (1) evaluated the impact of a computer-based educational programme compared to standard care and (2) examined whether different patterns of programme usage could be explained by demographic, medical and psychosocial factors. We involved 226 Swedish-speaking women diagnosed with early-stage breast cancer and scheduled for surgery. Primary outcomes were health self-efficacy and health care participation measured by the Comprehensive Health Enhancement Supportive System instrument. Secondary outcomes were anxiety and depression levels measured by the Hospital Anxiety and Depression scale. The Functional Assessment of Cancer Therapy-Breast and Sense of Coherence scales measured psychosocial factors for the study's secondary aim. Multi-level modelling revealed no statistically significant impact of the computer-based educational programme over time on the outcomes. Subsequent exploratory regression analysis revealed that older women with axillary dissection and increased physical well-being were more likely to use the programme. Furthermore, receiving post-operative chemotherapy and increased meaningfulness decreased the likelihood of use. Providing reliable and evidence-based medical and rehabilitation information via a computer-based programme might not be enough to influence multi-dimensional outcomes in women diagnosed with breast cancer. The use of these programmes should be further explored to promote adherence to e-Health supportive interventions.

Effects of requested, forced and denied shift schedule change on work ability and health of nurses in Europe -results from the European NEXT-Study

BACKGROUND

Previous cross-sectional findings from the European Nurses Early Exit Study (NEXT) show that nurses who were dissatisfied with their work schedule tended to consider leaving the nursing profession. Mediating factors in this decision process may be caused by self-perceived poor work ability and/or health. The aim of this paper is to investigate changes in work ability and general health among nurses in relation to requested, forced and denied change of shift schedule.

METHODS

Longitudinal data from the NEXT Study was used. In total 11,102 nurses from Belgium, Germany, Finland, the Netherlands, Poland, Slovakia, France and Italy completed both the 'basic questionnaire' (t1) and the '12 month follow-up questionnaire' (t2). To examine the time-effect (repeated measures) and the group-effect of five defined groups of nurses on the Work Ability Index (WAI) and general health (SF36), an adjusted 2-way analysis of covariance (ANCOVA) was performed.

RESULTS

The nurses who wanted to, but could not change their shifts during the 12 month follow-up had the lowest initial and follow-up scores for WAI (t1: 37.6, t2: 36.6, p <0.001), lowest general health (t1: 63.9, t2: 59.2, p <0.001) and showed the highest decrease in both outcomes. Shift pattern change in line with the nurses' wishes was associated with improved work ability and to a lesser comparatively low extent with increased decline in health scores. A forced change of shift against the nurses' will was significantly associated with a deteriorating work ability and health.

CONCLUSIONS

The findings would suggest that nurses' desire to change their shift patterns may be an indicator for perceived low work ability and/or low health. The results also indicate that fulfilling nurses' wishes with respect to their shift work pattern may improve their personal resources such as work ability and - to somewhat lesser extent - health. Disregarding nurses' preferences, however, bears the risk for further resource deterioration. The findings imply that shift schedule organization may constitute a valuable preventive tool to promote nurses' work ability and - to lesser extent - their perceived health, not least in aging nursing work forces.

Evaluation of time-varying and cumulative effects in nursing in a longitudinal study

BACKGROUND

Traditional statistics in longitudinal data analysis are likely to be insufficient in nursing studies, in which the time varying characteristics of explanatory variables and cumulative effects require additional consideration.

OBJECTIVES

The aims of this study were to introduce alternative longitudinal approaches for incorporating time-varying variables and cumulative effects, to discuss their strengths, and to highlight key issues that nursing researchers should recognize before and while undertaking such analyses.

RESULTS

The three alternative models provide differing analytical outcomes based on the research focus. The baseline tracking model was used to estimate the stability effect of an intervention program, detecting risk factors early. The temporal sequence of potential cause and effect was incorporated further in the time-dependent model. The cumulative model was used to explore whether cumulative intervention effects existed.

CONCLUSION

Nurse researchers should incorporate alternative methods into the longitudinal data analysis tools they commonly use when facing explanatory variables with time variations or cumulative effects on the variable being measured.

In vivo calibration of microdialysis using infusion of stable-isotope labeled neurotransmitters

In vivo calibration of microdialysis probes is required for interpreting measured concentrations. The most popular method of in vivo calibration is no-net-flux (NNF), which requires infusing several concentrations of neurotransmitters to determine in vivo recoveries (extraction fraction or Ed) and extracellular concentrations. A new method for in vivo calibration of microdialysis of neurotransmitters using glutamate (GLU) and dopamine (DA) as model analytes is reported. (13)C6-DA and (13)C5-GLU were perfused through microdialysis probes as internal calibrators. Using liquid chromatography with mass spectrometry, it was possible to distinguish the (13)C-forms from the endogenous forms of each neurotransmitter. Ed was directly calculated by measuring the loss of the (13)C-forms during infusion. The measured endogenous (12)C forms of the neurotransmitters could be corrected for Ed to give calibrated extracellular concentrations in vivo. Retrodialysis of stable-isotope-labeled (SIL) neurotransmitters gave Ed and extracellular concentrations of (13)C5-GLU and (13)C6-DA that matched no-net-flux measurements; however, the values were obtained in a fraction of time because no added measurements were required to obtain the calibration. Ed was reduced during uptake inhibition for GLU and DA when measured by SIL retrodialysis. Because Ed is directly measured at each microdialysis fraction, it was possible to monitor changes in Ed under transient conditions created by systemic injection of uptake inhibitors. The results show that DA and GLU concentrations are underestimated by as much as 50% if not corrected for Ed during uptake inhibition. SIL retrodialysis provides equivalent information to NNF at much reduced time and animal use.

Single-case experimental designs: a systematic review of published research and current standards

This article systematically reviews the research design and methodological characteristics of single-case experimental design (SCED) research published in peer-reviewed journals between 2000 and 2010. SCEDs provide researchers with a flexible and viable alternative to group designs with large sample sizes. However, methodological challenges have precluded widespread implementation and acceptance of the SCED as a viable complementary methodology to the predominant group design. This article includes a description of the research design, measurement, and analysis domains distinctive to the SCED; a discussion of the results within the framework of contemporary standards and guidelines in the field; and a presentation of updated benchmarks for key characteristics (e.g., baseline sampling, method of analysis), and overall, it provides researchers and reviewers with a resource for conducting and evaluating SCED research. The results of the systematic review of 409 studies suggest that recently published SCED research is largely in accordance with contemporary criteria for experimental quality. Analytic method emerged as an area of discord. Comparison of the findings of this review with historical estimates of the use of statistical analysis indicates an upward trend, but visual analysis remains the most common analytic method and also garners the most support among those entities providing SCED standards. Although consensus exists along key dimensions of single-case research design, and researchers appear to be practicing within these parameters, there remains a need for further evaluation of assessment and sampling techniques and data analytic methods.