Reliability and validity of gait analysis by android-based smartphone

Smartphones are very common devices in daily life that have a built-in tri-axial accelerometer. Similar to previously developed accelerometers, smartphones can be used to assess gait patterns. However, few gait analyses have been performed using smartphones, and their reliability and validity have not been evaluated yet. The purpose of this study was to evaluate the reliability and validity of a smartphone accelerometer. Thirty healthy young adults participated in this study. They walked 20 m at their preferred speeds, and their trunk accelerations were measured using a smartphone and a tri-axial accelerometer that was secured over the L3 spinous process. We developed a gait analysis application and installed it in the smartphone to measure the acceleration. After signal processing, we calculated the gait parameters of each measurement terminal: peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone (p<0.001). All the gait parameter results obtained by the smartphone showed statistically significant and considerable correlations with the same parameter results obtained by the tri-axial accelerometer (PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; p<0.01). Our study indicates that the smartphone with gait analysis application used in this study has the capacity to quantify gait parameters with a degree of accuracy that is comparable to that of the tri-axial accelerometer.     

Concurrent validity of the Microsoft Kinect for Windows v2 for measuring spatiotemporal gait parameters

This paper presents a study to evaluate the concurrent validity of the Microsoft Kinect for Windows v2 for measuring the spatiotemporal parameters of gait. Twenty healthy adults performed several sequences of walks across a GAITRite mat under three different conditions: usual pace, fast pace, and dual task. Each walking sequence was simultaneously captured with two Kinect for Windows v2 and the GAITRite system. An automated algorithm was employed to extract various spatiotemporal features including stance time, step length, step time and gait velocity from the recorded Kinect v2 sequences. Accuracy in terms of reliability, concurrent validity and limits of agreement was examined for each gait feature under different walking conditions. The 95% Bland–Altman limits of agreement were narrow enough for the Kinect v2 to be a valid tool for measuring all reported spatiotemporal parameters of gait in all three conditions. An excellent intraclass correlation coefficient (ICC_{2, 1}) ranging from 0.9 to 0.98 was observed for all gait measures across different walking conditions. The inter trial reliability of all gait parameters were shown to be strong for all walking types (ICC_{3, 1} > 0.73). The results of this study suggest that the Kinect for Windows v2 has the capacity to measure selected spatiotemporal gait parameters for healthy adults.     

Microprocessor-based gait analysis system to retrain Trendelenburg gait

A microprocessor-based gait analysis system is described that uses two electromyogram (EMG) amplifiers, two foot switches and an audio feedback device to allow the retraining of one type of improper gait, where the hip abductors (gluteus medius muscles) are weak on one side of the body, causing the opposite hip to drop during the swing phase of gait (Trendelenburg gait). As the abnormality is strictly on one side of the body in most people, the circuitry is minimised, as gait can be analysed by only comparing muscle activity in the affected gluteus medius muscle with that in the unaffected gluteus medius muscle, through the EMG. Two foot contact switches are used to help assess timing of the step cycle. If gait is different on the two sides of the body, an audio cue directs the patient to correct the abnormality by increasing activity on the affected side. The device is tested on five patients. Trendelenburg gait is reduced by an average of 29 degrees through the use of the device. The average stride length at the beginning of the study is 0.32±0.3 m. By the end of the study, the stride length is increased to 0.45±0.2m for the entire group of five subjects. The speed of gait has increased from 1.6±0.4 kmh⁻¹ to 3.1±0.5 kmh⁻¹.     

Validity of the Optogait photoelectric system for the assessment of spatiotemporal gait parameters

The purpose of this study was to evaluate the discriminant and concurrent (criterion-related) validity of a recently introduced floor-based photocell system (Optogait, Microgate, Bolzano, Italy) with a validated electronic walkway for the assessment of spatiotemporal gait parameters. Fifteen patients (mean age ± standard deviation: 65 ± 7 years) with total knee arthroplasty and 15 healthy matched control subjects were asked to walk at different velocities while gait variables were recorded simultaneously by the two instruments. The Optogait and the criterion instrument detected the same differences in walking parameters between patients and controls. Intraclass correlation coefficients ranged between 0.933 (swing time) and 0.999 (cycle time, cadence and walking speed). Cycle time and stance time were significantly longer, while swing time, step length, cadence and walking speed were significantly lower for Optogait (p < 0.001) compared to the criterion instrument. The Optogait system demonstrated high discriminant and concurrent validity with an electronic walkway for the assessment of spatiotemporal gait parameters in orthopedic patients and healthy controls. However, the two measuring instruments cannot be used interchangeably for quantitative gait analysis, and further validation of floor-based photocell technology is warranted.     

Warding off a tyranny of reliability and validity

Researchers in the healthcare communication field come from many different educational backgrounds. Such diversity generally strengthens a field, but sometimes a set of beliefs or a particular orthodoxy may predominate in ways that are negative. We discuss one such example, noting how the research culture deriving from training in schools of education treats the concepts of reliability and validity. We note that some researchers working in fields such as medical education and healthcare communication use the terms “reliable” and “valid” loosely or even incorrectly, often referring to them as a single catch-phrase. More importantly, we caution healthcare communication researchers against a tyranny of reliability and validity in which researchers feel pressure to avoid creating unique instruments to study new questions, instead using instruments with previously demonstrated reliability and validity even when these may not directly capture the concept of interest. This practice is motivated by realistic fears that reviewers and editors will disapprove of their work because the instruments used are not known to be “reliable and valid.” We encourage the research community to take a more balanced approach wherein originality is not stifled, and in which creativity and rigor exist side by side.     

The technique of gait analysis using a Coda-3 motion analysis system

Gait analysis using Code-3 provides information which allows individual gait to be characterised with little interference to the patient. It is an ideal method for analysing gait in patients with cerebral palsy. Because of the ease with which this information is now available using Coda-3, gait analysis can now be performed on all ambulant patients in whom surgery is contemplated.     

Florida Obsessive-Compulsive Inventory: development, reliability, and validity

The Florida Obsessive-Compulsive Inventory (FOCI) is a new self-report questionnaire that has separate scales for symptom enumeration (The Checklist) and evaluation of symptom severity (Severity Scale). The present research investigated the FOCI in a sample of 113 patients with obsessive-compulsive disorder (OCD). The results indicated that the FOCI Severity Scale is internally consistent (alpha = .89) and highly correlated with the total score from the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS; Goodman et al., 1989 a). The correlations of the FOCI Severity Scale with measures of depression and global severity of psychopathology were similar to those obtained with the Y-BOCS Total Severity Score. The FOCI Symptom Checklist had adequate reliability (K-R 20 = .83) and moderate correlations (rs < .45) with the FOCI Severity Scale, the Y-BOCS scales, and measures of depression and severity of psychopathology. These findings imply concurrent validity for the FOCI Severity Scale. A strength of the FOCI is that it offers a quick evaluation of both presence and severity of OCD symptoms. An important limitation is that the FOCI does not assess the severity of individual symptoms.     

The construction, reliability and validity of a Japanese Need for Closure Scale

The purpose of this study was to develop a Japanese Need for Closure Scale. In Study 1, Webster and Kruglanski's (1994) Need for Closure Scale was translated into Japanese, and administered to 240 undergraduates. Factor analysis of the Japanese version indicated that a three-factor structure was most appropriate. In Study 2, a revised scale was developed based on the result of Study 1, and administered to 577 undergraduates. Analysis of the revised Japanese Need for Closure Scale showed that it had sufficient internal consistency and test-retest reliability. In addition, confirmatory factor analysis indicated that the scale had a multidimensional structure. In Study 3, the scale was administered together with five relevant personality scales to 340 undergraduates, and sufficient construct validity of the scale was demonstrated.     

The Cancode interaction analysis system in the oncological setting: reliability and validity of video and audio tape coding

Cancode is a computerized interaction analysis system developed for cancer consultations. This paper assesses its reliability and validity, and compares the use of audio versus video tape; by assessing 30 consultations between an actor and 10 oncologists. Weighted Kappa inter- and intra-rater scores ranged from 0.5 to 1.0 and 0.58-1.0, respectively, and use of video tape did not alter verbal coding. Factor analysis of verbal codes revealed two factors, 'verbal control' and 'verbal support'. Verbal and non-verbal doctor behavior differed by patient type ('verbal support' P = 0.007, 'verbal control' P = 0.004, 'Responsiveness' P = 0.000, and 'Immediacy' P = 0.000). Inter-doctor variation was noted for 'verbal support' (P = 0.000) and 'Relaxation' (P = 0.000). 'Responsiveness' was negatively correlated with 'verbal support' (-0.58) and 'verbal control' (-0.65). Cancode is reliable, valid and sensitive to doctors behavioral changes. For a more passive patient, the doctor may switch from a 'cure' to 'care' oriented consult, responding to psycho-social instead of informational needs.     

A daily stress inventory: Development,reliability, and validity

This article describes the development of the Daily Stress Inventory, a measure introduced to provide researchers and clinicians with a psychometrically sound self-report instrument for the daily assessment of the sources and individualized impact of relatively minor stressful events. It was designed to assess sources of stress not typically assessed by major life-event scales. Generalizability coefficients indicate that the scale has significant homogeneity and a useful degree of stability. Several studies investigating the concurrent and construct validities suggest that the scale measures the construct commonly referred to as "stress." Implications for uses in theoretical and basic research as well as clinical assessment are discussed.     

The affective lability scales: development, reliability, and validity

A self-report measure of changeable affect was developed, with a goal of identification of patterns of instability in mood. Scales measuring lability in anxiety, depression, anger, and hypomania, and labile shifts between anxiety and depression and hypomania and depression were constructed. These scales were then evaluated for internal consistency, retest reliability, score stability across samples, and for discriminant validity through assessment of association with measures of dysphoria and intensity of affect. The final versions of the scales are short scales that yield highly stable estimates of affect lability. It was noted that these scales are highly correlated in unselected students and it is believed that ongoing research with clinical populations will better allow for determination of the independence of these scales.     

The PTSD interview: rationale, description, reliability, and concurrent validity of a DSM-III-based technique

This paper describes the PTSD Interview (PTSD-I). It was developed to meet four specifications: (a) close correspondence to DSM-III standards; (b) binary present/absent and continuous severity/frequency outputs on each symptom and the entire syndrome; (c) administrable by trained subprofessionals; and (d) substantial reliability and validity. It was written to meet the first three criteria. It demonstrated very high internal consistency (alpha = .92) and test-retest reliability (Total score r = .95; diagnostic agreement = 87%). It correlated strongly with parallel DIS criteria (Total score vs. DIS diagnosis rbis = .94, sensitivity = .89, specificity = .94, overall hit rate = .92, and kappa = .84). Earlier studies revealed correlations with a military stress scale and Keane et al.'s MMPI PTSD subscale. It is apparently the only PTSD instrument that meets all of the above criteria.     

Factor structure, validity and reliability of the Cambridge Worry Scale in a pregnant population

This article presents the Cambridge Worry Scale (CWS), a content-based measure for assessing worries, and discusses its psychometric properties based on a longitudinal study of 1,207 pregnant women. Principal components analysis revealed a four-factor structure of women's concerns during pregnancy: socio-medical, own health, socio-economic and relational. The measure demonstrated good reliability and validity. Total CWS scores were strongly associated with state and trait anxiety (convergent validity) but also had significant and unique predictive value for mood outcomes (discriminant validity). The CWS discriminated better between women with different reproductive histories than measures of state and trait anxiety. We conclude that the CWS is a reliable and valid tool for assessing the extent and content of worries in specific situations.