scholarly journals Beyond smartphones and sensors: choosing appropriate statistical methods for the analysis of longitudinal data

2018 ◽  
Vol 25 (12) ◽  
pp. 1669-1674 ◽  
Author(s):  
Ian Barnett ◽  
John Torous ◽  
Patrick Staples ◽  
Matcheri Keshavan ◽  
Jukka-Pekka Onnela
Keyword(s):  
Longitudinal Study ◽  
Longitudinal Data ◽  
Statistical Methods ◽  
Statistical Models ◽  
Repeated Measures ◽  
Extended Period ◽  
Multiple Comparisons ◽  
Digital Data ◽  
Digital Phenotyping ◽  
Improper Use

AbstractObjectivesAs smartphones and sensors become more prominently used in mobile health, the methods used to analyze the resulting data must also be carefully considered. The advantages of smartphone-based studies, including large quantities of temporally dense longitudinally captured data, must be matched with the appropriate statistical methods in order draw valid conclusions. In this paper, we review and provide recommendations in 3 critical domains of analysis for these types of temporally dense longitudinal data and highlight how misleading results can arise from improper use of these methods.Target AudienceClinicians, biostatisticians, and data analysts who have digital phenotyping data or are interested in performing a digital phenotyping study or any other type of longitudinal study with frequent measurements taken over an extended period of time.ScopeWe cover the following topics: 1) statistical models using longitudinal repeated measures, 2) multiple comparisons of correlated tests, and 3) dimension reduction for correlated behavioral covariates. While these 3 classes of methods are frequently used in digital phenotyping data analysis, we demonstrate via actual clinical studies data that they may sometimes not perform as expected when applied to novel digital data.

scholarly journals Novel Application of Statistical Methods to Identify New Urinary Incontinence Risk Factors

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Theophilus O. Ogunyemi ◽  
Mohammad-Reza Siadat ◽  
Suzan Arslanturk ◽  
Kim A. Killinger ◽  
Ananias C. Diokno
Keyword(s):  
Risk Factors ◽  
Urinary Incontinence ◽  
Longitudinal Data ◽  
Statistical Methods ◽  
Repeated Measures ◽  
Significant Risk ◽  
Large Data ◽  
Data Sets ◽  
Predictive Index ◽  
Urine Loss

Longitudinal data for studying urinary incontinence (UI) risk factors are rare. Data from one study, the hallmark Medical, Epidemiological, and Social Aspects of Aging (MESA), have been analyzed in the past; however, repeated measures analyses that are crucial for analyzing longitudinal data have not been applied. We tested a novel application of statistical methods to identify UI risk factors in older women. MESA data were collected at baseline and yearly from a sample of 1955 men and women in the community. Only women responding to the 762 baseline and 559 follow-up questions at one year in each respective survey were examined. To test their utility in mining large data sets, and as a preliminary step to creating a predictive index for developing UI, logistic regression, generalized estimating equations (GEEs), and proportional hazard regression (PHREG) methods were used on the existing MESA data. The GEE and PHREG combination identified 15 significant risk factors associated with developing UI out of which six of them, namely, urinary frequency, urgency, any urine loss, urine loss after emptying, subject’s anticipation, and doctor’s proactivity, are found most highly significant by both methods. These six factors are potential candidates for constructing a future UI predictive index.

scholarly journals A longitudinal study of perceived stress and cortisol responses in an undergraduate student population from India

2019 ◽  
Author(s):  
Anuradha Batabyal ◽  
Anindita Bhattacharya ◽  
Maria Thaker ◽  
Shomen Mukherjee
Keyword(s):  
Longitudinal Study ◽  
Perceived Stress ◽  
Salivary Cortisol ◽  
Undergraduate Student ◽  
Repeated Measures ◽  
Stressful Events ◽  
Continuous Assessment ◽  
One Year ◽  
Distress Scale ◽  
Psychological Parameters

AbstractYoung adults entering into college experience immense shifts in both personal and professional environments and this may result in some of them experiencing a lot of stress and difficulty in coping with their new surroundings. Such potentially stressful events may trigger multiple psychological as well as physiological effects. The current study investigated multiple psychological parameters such as PSS14 (Perceived Stress Scale), K10 (distress scale) and positive mood measures, along with salivary cortisol levels, in a repeated measures longitudinal study of first year students (~ 19 years of age) enrolled at a residential college in India. Six salivary cortisol samples were collected over a one-year period from 20 students. On each sampling day, a questionnaire designed to evaluate (K10, PSS14 and Mood) psychological parameters was also administered.Overall, men showed a significantly lower level of salivary cortisol compared to women. Men also showed a decrease in perceived stress (PSS14) and distress (K10) with time. However, women reported similar perceived stress and distress levels all year round. Academic stress was reported by the students to be the most important stressor, whereas financial stress was reported the least number of times by all participants. Our results suggest that men seem to have a better capability to adjust to the new environment of a residential program with time. In contrast, women show an elevation in salivary cortisol at the end of the semester (the final assessment stage) in spite of a continuous assessment curricular design. This study not only provides an important glimpse into the sex differences in stress response in the first one year of joining an undergraduate program, but it also provides a valuable longitudinal dataset from the Indian undergraduate student cohort which is lacking in literature.

scholarly journals Logical and Methodological Issues Affecting Genetic Studies of Humans Reported in Top Neuroscience Journals

2018 ◽  
Vol 30 (1) ◽  
pp. 25-41 ◽  
Author(s):  
Clara R. Grabitz ◽  
Katherine S. Button ◽  
Marcus R. Munafò ◽  
Dianne F. Newbury ◽  
Cyril R. Pernet ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Multiple Comparisons ◽  
Effect Sizes ◽  
Genetic Associations ◽  
Methodological Issues ◽  
Increased Risk ◽  
Depth Analysis ◽  
Standardized Reporting ◽  
Supplementary Material ◽  
Methodological Problems

Genetics and neuroscience are two areas of science that pose particular methodological problems because they involve detecting weak signals (i.e., small effects) in noisy data. In recent years, increasing numbers of studies have attempted to bridge these disciplines by looking for genetic factors associated with individual differences in behavior, cognition, and brain structure or function. However, different methodological approaches to guarding against false positives have evolved in the two disciplines. To explore methodological issues affecting neurogenetic studies, we conducted an in-depth analysis of 30 consecutive articles in 12 top neuroscience journals that reported on genetic associations in nonclinical human samples. It was often difficult to estimate effect sizes in neuroimaging paradigms. Where effect sizes could be calculated, the studies reporting the largest effect sizes tended to have two features: (i) they had the smallest samples and were generally underpowered to detect genetic effects, and (ii) they did not fully correct for multiple comparisons. Furthermore, only a minority of studies used statistical methods for multiple comparisons that took into account correlations between phenotypes or genotypes, and only nine studies included a replication sample or explicitly set out to replicate a prior finding. Finally, presentation of methodological information was not standardized and was often distributed across Methods sections and Supplementary Material, making it challenging to assemble basic information from many studies. Space limits imposed by journals could mean that highly complex statistical methods were described in only a superficial fashion. In summary, methods that have become standard in the genetics literature—stringent statistical standards, use of large samples, and replication of findings—are not always adopted when behavioral, cognitive, or neuroimaging phenotypes are used, leading to an increased risk of false-positive findings. Studies need to correct not just for the number of phenotypes collected but also for the number of genotypes examined, genetic models tested, and subsamples investigated. The field would benefit from more widespread use of methods that take into account correlations between the factors corrected for, such as spectral decomposition, or permutation approaches. Replication should become standard practice; this, together with the need for larger sample sizes, will entail greater emphasis on collaboration between research groups. We conclude with some specific suggestions for standardized reporting in this area.

Prediction of Human Segment Inertias during Pregnancy

1996 ◽  
Vol 12 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Robert K. Jensen ◽  
Tina Treitz ◽  
Sylvie Doucet
Keyword(s):  
Longitudinal Study ◽  
Repeated Measures ◽  
Center Of Mass ◽  
Predictor Variables ◽  
Radius Of Gyration ◽  
Regression Equations ◽  
Lower Trunk ◽  
The Third ◽  
Cylinder Model ◽  
Linear Regressions

The purpose of this study was to develop prediction equations to estimate mass, radius to the center of mass (CM), and principal moments of the segments during pregnancy. Nonlinear regression equations were determined for the lower trunk, upper trunk, and thigh. The third sampling month of a longitudinal study was used (Sample 1,n= 15). The nonlinear regressions were then used to predict segment inertias above and below the third sampling month (Sample 2, the remaining 74 measurements). For the remaining segments, body mass and segment lengths were used as predictor variables for mass, radius to CM, and radius of gyration about the centroidal axes. The remaining seven segments did not change substantially during pregnancy, and the means of the repeated measures were used for the simple linear regressions. Eighteen of the 28 regressions and all of the CM regressions were significant. With pregnant subjects it is recommended that these regressions be used if application of the elliptical cylinder model is not possible.

Modelling multiple outcomes in repeated measures studies: Comparing aesthetic eyelid surgery techniques

2020 ◽  
pp. 1471082X2094331
Author(s):  
Wagner H. Bonat ◽  
Ricardo R. Petterle ◽  
Priscilla Balbinot ◽  
Alexandre Mansur ◽  
Ruth Graf
Keyword(s):  
Longitudinal Data ◽  
Repeated Measures ◽  
Hypothesis Test ◽  
Covariance Structure ◽  
Likelihood Estimation ◽  
Horizontal Line ◽  
Multiple Outcomes ◽  
Forehead Lift ◽  
Eyelid Surgery ◽  
Lateral Canthus

We propose a multivariate regression model to deal with multiple outcomes along with repeated measures in the context of longitudinal data analysis. Our model allows for flexible and interpretable modelling of the covariance structure within outcomes by using a linear combination of known matrices, while the generalized Kronecker product is employed to take into account the correlation between outcomes. We present maximum likelihood estimation along with extensions of the classical multivariate analysis of variance and multiple comparison hypothesis tests to deal with multivariate longitudinal data. The model and the associated multivariate hypothesis test are motivated by a prospective study conducted to compare three aesthetic eyelid surgery techniques, namely blepharoplasty, endoscopic forehead lift and endoscopic forehead lift associated with blepharoplasty. The effect of the techniques was assessed using measurements of a horizontal line through pupil centre and then three vertical lines, which go in direction to lateral canthus, middle pupil and medial canthus to the top of the brow. In this study, 30 female patients were randomly divided into three groups. Preoperative measurements were compared with postoperative measurements taken 30 days, 90 days and 10 years after the surgery. The presented multivariate model provided a better fit than its univariate counterpart. The results showed that the three surgery techniques tend to increase all considered outcomes in a long-term perspective, that is, from preoperative to 10 years postoperative evaluations. The only exception was for the outcome lateral eyebrow, for which the blepharoplasty had no significant effect.

scholarly journals Contributing Factors, Prevention, and Management of Playing-Related Musculoskeletal Disorders Among Flute Players Internationally

2014 ◽  
Vol 29 (3) ◽  
pp. 155-162 ◽  
Author(s):  
Karen Lonsdale ◽  
E-Liisa Laakso ◽  
Vanessa Tomlinson
Keyword(s):  
Longitudinal Study ◽  
Teaching Methods ◽  
Management Strategies ◽  
Extended Period ◽  
Education History ◽  
Contributing Factors ◽  
Current Survey ◽  
History Of ◽  
Set Up ◽  
The Relationship

Major studies have shown that flutists report playing-related pain in the neck, middle/upper back, shoulders, wrists, and hands. The current survey was designed to establish the injury concerns of flute players and teachers of all backgrounds, as well as their knowledge and awareness of injury prevention and management. Questions addressed a range of issues including education, history of injuries, preventative and management strategies, lifestyle factors, and teaching methods. At the time of the survey, 26.7% of all respondents were suffering from flute playing-related discomfort or pain; 49.7% had experienced flute playing-related discomfort or pain that was severe enough to distract while performing; and 25.8% had taken an extended period of time off playing because of discomfort or pain. Consistent with earlier studies, the most common pain sites were the fingers, hands, arms, neck, middle/upper back, and shoulders. Further research is needed to establish possible links between sex, instrument types, and ergonomic set up. Further investigation is recommended to ascertain whether certain types of physical training, education, and practice approaches may be more suitable than current methods. A longitudinal study researching the relationship between early education, playing position, ergonomic set-up, and prevalence of injury is recommended.

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