The Use of Indices in Surveys

The paper deals with some new indices for ordinal data that arise from sample surveys. Their aim is to measure the degree of concentration to the “positive” or “negative” answers in a given question. The properties of these indices are examined. Moreover, methods for constructing confidence limits for the indices are discussed and their performance is evaluated through an extensive simulation study. Finally, the values of the indices defined and their confidence intervals are calculated for an example with real dataMultinomial proportions, Ordinal data, Indices, Confidence intervals, Sample surveys

On Certain Indices for Ordinal Data with Unequally Weighted Classes

In this paper, some new indices for ordinal data are introduced. These indices have been developed so as to measure the degree of concentration on the “small” or the “large” values of a variable whose level of measurement is ordinal. Their advantage in relation to other approaches is that they ascribe unequal weights to each class of values. Although, they constitute a useful tool in various fields of applications, the focus here is on their use in sample surveys and specifically in situations where one is interested in taking into account the “distance” of the responses from the “neutral” category in a given question. The properties of these indices are examined and methods for constructing confidence intervals for their actual values are discussed. The performance of these methods is evaluated through an extensive simulation study.

The Use of Indices in Surveys

The paper deals with some new indices for ordinal data that arise from sample surveys. Their aim is to measure the degree of concentration to the “positive” or “negative” answers in a given question. The properties of these indices are examined. Moreover, methods for constructing confidence limits for the indices are discussed and their performance is evaluated through an extensive simulation study. Finally, the values of the indices defined and their confidence intervals are calculated for an example with real dat

The Use of Indices in Surveys

The paper deals with some new indices for ordinal data that arise from sample surveys. Their aim is to measure the degree of concentration to the “positive” or “negative” answers in a given question. The properties of these indices are examined. Moreover, methods for constructing confidence limits for the indices are discussed and their performance is evaluated through an extensive simulation study. Finally, the values of the indices defined and their confidence intervals are calculated for an example with real dat

On Certain Indices for Ordinal Data with Unequally Weighted Classes

In this paper, some new indices for ordinal data are introduced. These indices have been developed so as to measure the degree of concentration on the “small” or the “large” values of a variable whose level of measurement is ordinal. Their advantage in relation to other approaches is that they ascribe unequal weights to each class of values. Although, they constitute a useful tool in various fields of applications, the focus here is on their use in sample surveys and specifically in situations where one is interested in taking into account the “distance” of the responses from the “neutral” category in a given question. The properties of these indices are examined and methods for constructing confidence intervals for their actual values are discussed. The performance of these methods is evaluated through an extensive simulation study

On Certain Indices for Ordinal Data with Unequally Weighted Classes

In this paper, some new indices for ordinal data are introduced. These indices have been developed so as to measure the degree of concentration on the “small” or the “large” values of a variable whose level of measurement is ordinal. Their advantage in relation to other approaches is that they ascribe unequal weights to each class of values. Although, they constitute a useful tool in various fields of applications, the focus here is on their use in sample surveys and specifically in situations where one is interested in taking into account the “distance” of the responses from the “neutral” category in a given question. The properties of these indices are examined and methods for constructing confidence intervals for their actual values are discussed. The performance of these methods is evaluated through an extensive simulation study

On Certain Indices for Ordinal Data with Unequally Weighted Classes

In this paper, some new indices for ordinal data are introduced. These indices have been developed so as to measure the degree of concentration on the “small” or the “large” values of a variable whose level of measurement is ordinal. Their advantage in relation to other approached is that they ascribe unequal weights to each class of values. Although, they constitute a useful tool in various fields of applications, the focus here is on their use in sample surveys and more specifically in situations where one is interested in taking into account the “distance” of the responses from the “neutral” category in a given question. The properties of these indices are examined and methods for constructing confidence intervals for their actual values are discussed. The performance of these methods is evaluated through an extensive simulation stud

Ankle contractures in people with multiple sclerosis : Implications, measurement and treatment

Contractures (loss of passive joint range of motion) are common in people with Multiple Sclerosis (MS) and the ankle joint is the most common site. Ankle contractures are disabling as they impede ankle range of motion (ROM). Full ankle ROM is essential for normal ambulation therefore, ankle contractures play a role in the loss of mobility and physical independence in people with MS. Methods explored in this thesis focused on the implications, measurement and subsequent treatment of ankle contractures in people with MS. Implications Reduced ankle ROM was associated with compromised heel-to-toe progression. Compared to healthy controls, people with MS spent less time in contact phase (7.8% vs 25.1%) and more time in the mid stance phase of gait (57.3% vs 33.7%). Significant differences were detected in people with MS between the affected and less-affected limbs for contact (7.8% vs 15.3%) and mid stance (57.3% and 47.1%) phases. Our method of heel-to-toe progression revealed subtle gait impairments that were not detectable using standard spatiotemporal gait parameters. Reduced ankle ROM was associated with an increase in compensatory head and pelvic movements that influenced gait stability in people with MS. Compared to healthy controls, people with MS had greater asymmetry in head and pelvic movements (Cohen’s d=1.85 & 1.60) and were less stable (Cohen’s d=-1.61 to -3.06) even after adjusting for slower walking speeds. Our method of screening for excessive compensatory movements provided clinically-important information that impacted on mobility, symmetry and stability in people with MS. Measurement Current measurement techniques lack sensitivity to detect ankle impairments in people with MS. We developed a device (Flexometer) to produce standardised (torque-controlled) and reproducible measurements of passive ankle dorsiflexion. The Flexometer proved to be a valid and reliable method (ICC’s 0.94 – 0.99) for assessing ankle ROM in people with MS. The accuracy of this device provides clinicians and researchers with a tool capable of accurate diagnoses and subsequent treatment of ankle contractures in people with MS. Treatment Ankle contractures alter muscle morphology leading to shorter, stiffer muscle fascicles in people with MS. According to our systematic review, there appears to be evidence to support the use of eccentric exercise to improve muscle fascicle length and ankle ROM. Therefore, adaptations from eccentric exercise could potentially target deficits present within muscles affected by contracture in people with MS. We explored the effects of backwards-walking-downhill (eccentric exercise) as a therapeutic modality for the management of ankle joint contractures in people with MS. Results indicated backwards-walking-downhill is a novel, safe and feasible training modality in people with MS with an ankle contracture. Additionally, compared to baseline measurements, MS participants improved by approximately 10 degrees in both passive and active ROM. While clinical outcomes (passive and active ROM) were promising, translation to clinically meaningful changes in walking function require further examination

Gyroscopic corrections improve wearable sensor data prior to measuring dynamic sway in the gait of people with Multiple Sclerosis

Accelerometers are incorporated into many consumer devices providing new ways to monitor gait, mobility, and fall risk. However, many health benefits have not been realised because of issues with data quality that results from gravitational ‘cross-talk’ when the wearable device is tilted. Here we present an adaptive filter designed to improve the quality of accelerometer data prior to measuring dynamic pelvic sway patterns during a six minute walk test in people with and without Multiple Sclerosis (MS). Optical motion capture was used as the gold standard. Improved wearable device accuracy (≤4.4% NRMSE) was achieved using gyroscopic corrections and scaling filter thresholds by step frequency. The people with MS presented significantly greater pelvis sway range to compensate for their lower limb weaknesses and joint contractures. The visualisation of asymmetric pelvic sway in people with MS illustrates the potential to better understand their mobility impairments for reducing fall risk