Exploring Concepts of Social Mobility

This chapter has two purposes. The first is to define clearly different social mobility concepts and components. The second is to embed these concepts and components into a larger context of social mobility research. The core of the chapter develops six mobility concepts and their measures as well as six macromobility components and their measures. The next section relates these concepts and components to issues in the mobility literature. The chapter concludes with a checklist of suggestions for conducting and presenting social mobility research: being explicit about several preliminaries—outcome of interest, context, and level of analysis—and then four steps—question, mobility concept(s), mobility measure(s), and empirical findings.

Runout Number: A New Metric for Landslide Runout Characterization

ABSTRACT Landslide runout has traditionally been quantified by the height-to-length ratio, H/L, which, in many cases, is strongly influenced by the slope of the runout path. In this study, we propose an alternative mobility measure, the unitless Runout Number, measured as the landslide length divided by the square root of the landslide area, which characterizes landslide shape in terms of elongation. We used a database of 158 landslides of varying runout distances from locations in northern California, Oregon, and Washington state to compare the two runout measurement methods and explore their predictability using parameters that can be measured or estimated using geographic information systems. The Runout Number better describes the overall runout for several landslide and slope geometries. The two mobility measures show very little correlation to each other, indicating that the two parameters describe different landslide mobility mechanisms. When compared to predictive parameters shown by prior research to relate to landslide runout, the two runout measurement methods show different correlations. H/L correlates more strongly to initial slope angle, upslope contributing area, landslide area, and grain size distribution (percent clay, silt, total fines, and sand). The Runout Number correlates more strongly to planimetric curvature, upslope contributing area normalized by landslide area, and percent sand. Although these correlations are not necessarily strong enough for prediction, they indicate the validity of both runout measurement methods and the benefit of including both numbers when characterizing landslide mobility.

Cognitive Processing Speed Impairment Does Not Influence the Construct Validity of Six-Spot Step Test Performance in People With Multiple Sclerosis

Objective There is evidence supporting the construct validity of Six-Spot Step Test (SSST) performance as a functional mobility measure in people with multiple sclerosis (MS); however, it is unknown if cognitive processing speed (CPS) impairment confounds the construct validity of SSST performance in MS, as this test seemingly requires intact cognitive processing. The objective of this study was to examine the influence of CPS impairment on the construct validity and precision of SSST performance as a functional mobility measure in MS. Methods Participants (N = 213) completed the SSST, timed 25-foot walk, Six-Minute Walk Test, Timed “Up and Go” Test, Multiple Sclerosis Walking Scale-12, device-measured steps/day, and Late-Life Function and Disability Inventory, Patient-Determined Disease Steps, and the Symbol-Digit Modalities Test (SDMT) as a CPS measure. The overall sample was divided into subsamples with (n = 75) and without (n = 138) CPS impairment based on normative SDMT data. Correlations between SSST performance with other mobility outcomes in the overall sample and CPS impairment subsamples were examined and compared. SSST performance was compared relative to other mobility measures for differentiating MS walking function levels in people with and without CPS impairment. Results SSST performance was significantly and strongly correlated with most mobility outcomes in the overall sample and CPS impairment subsamples. The magnitudes of correlations between SSST performance with most mobility outcomes were not statistically different among subsamples. CPS impairment did not diminish the relative precision of SSST performance for differentiating walking function levels. Conclusions The presence of CPS impairment is not a source of invalidity or imprecision when interpreting SSST performance as a functional mobility measure among people with MS. Impact The SSST is a high-quality endpoint for inclusion in interventions targeting mobility in MS, regardless of CPS status. This information is critical for rehabilitation research and clinical practice given that mobility and cognitive impairment are highly prevalent, co-occurring, and disabling in MS.

Frequency of Impaired Spinal Mobility in Patients with Chronic Back Pain Compared to Patients with Early Axial Spondyloarthritis

Objective.To examine the frequency of impaired spinal mobility in patients with chronic back pain of short duration and to compare it with the frequency of impaired spinal mobility in patients with axial spondyloarthritis (axSpA), possible SpA, and no SpA.Methods.The SpondyloArthritis Caught Early (SPACE) cohort includes patients with chronic back pain (≥ 3 mos, ≤ 2 yrs, onset < 45 yrs). Spinal mobility was assessed with lateral spinal flexion, chest expansion, cervical rotation, occiput-to-wall distance, and lumbar flexion. Hip mobility was assessed with intermalleolar distance. Mobility measures were defined as impaired if below the 5th percentile reference curve from general population, adjusted for age and height when appropriate. Proportions of patients categorized with impaired mobility were examined with chi square.Results.In total, 393 patients with chronic back pain were included: 142 axSpA, 140 possible SpA, and 111 no SpA. Impairment in ≥ 1 mobility measure was present in 66% of all patients. The most frequently impaired mobility measure was lateral spinal flexion (40%), followed by chest expansion (22%), cervical rotation (18%), intermalleolar distance (17%), lumbar flexion (15%), and occiput-to-wall distance (11%). No statistically significant differences in proportion of patients with impaired spinal mobility were found between patients with axSpA and the other subgroups in any of the tests.Conclusion.Two out of 3 patients with chronic back pain of short duration had impaired spinal mobility compared to the general population. Impaired spinal mobility occurs as often in patients with early axSpA as in other forms of chronic back pain.