Maximum interpolable gap length in missing smartphone-based GPS mobility data

Passively-generated location data have the potential to augment mobility and transportation research, as demonstrated by a decade of research. A common trait of these data is a high proportion of missingness. Naïve handling, including list-wise deletion of subjects or days, or linear interpolation across time gaps, has the potential to bias summary results. On the other hand, it is unfeasible to collect mobility data at frequencies high enough to reflect all possible movements. In this paper, we describe the relationship between the temporal and spatial aspects of these data gaps, and illustrate the impact on measures of interest in the field of mobility. We propose a method to deal with missing location data that combines a so-called top-down ratio segmentation method with simple linear interpolation. The linear interpolation imputes missing data. The segmentation method transforms the set of location points to a series of lines, called segments. The method is designed for relatively short gaps, but is evaluated also for longer gaps. We study the effect of our imputation method for the duration of missing data using a completely observed subset of observations from the 2018 Statistics Netherlands travel study. We find that long gaps demonstrate greater downward bias on travel distance, movement events and radius of gyration as compared to shorter but more frequent gaps. When the missingness is unrelated to travel behavior, total sparsity can reach levels of up to 20% with gap lengths of up to 10 min while maintaining a maximum 5% downward bias in the metrics of interest. Temporal aspects can increase these limits; sparsity occurring in the evening or night hours is less biasing due to fewer travel behaviors

Choosing and using methodological search filters : searchers' views

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The influence of adjuvant systemic regimens on contralateral breast cancer risk and receptor subtype

Background: An increasing number of breast cancer (BC) survivors are at risk of developing contralateral breast cancer (CBC). We aimed to investigate the influence of various adjuvant systemic regimens on, subtype-specific, risk of CBC. Methods: This population-based cohort study included female patients diagnosed with first invasive BC between 2003 and 2010; follow-up was complete until 2016. Clinico-pathological data were obtained from the Netherlands Cancer Registry and additional data on receptor status through linkage with PALGA: the Dutch Pathology Registry. Cumulative incidences (death and distant metastases as competing risk) and hazard ratios (HRs) were estimated for all invasive metachronous CBC and CBC subtypes. Results: Of 83 144 BC patients, 2816 developed a CBC; the 10-year cumulative incidence was 3.8% (95% confidence interval [CI]=3.7% to 4.0%). Overall, adjuvant chemotherapy (HR=0.70, 95% CI=0.62 to 0.80), endocrine therapy (HR=0.46, 95% CI=0.41 to 0.52), and trastuzumab with chemotherapy (HR=0.57, 95% CI=0.45 to 0.73) were strongly associated with a reduced CBC risk. Specifically, taxane-containing chemotherapy (HR=0.48, 95% CI=0.36 to 0.62) and aromatase inhibitors (HR=0.32, 95% CI=0.23 to 0.44) were associated with a large CBC risk reduction. More detailed analyses showed that endocrine therapy statistically significantly decreased the risk of estrogen receptor (ER)-positive CBC (HR=0.41, 95% CI=0.36 to 0.47) but not ER-negative CBC (HR=1.32, 95% CI=0.90 to 1.93) compared with no endocrine therapy. Patients receiving chemotherapy for ER-negative first BC had a higher risk of ER-negative CBC from 5years of follow-up (HR=2.84, 95% CI=1.62 to 4.99) compared with patients not receiving chemotherapy for ER-negative first BC. Conclusion: Endocrine therapy, chemotherapy, as well as trastuzumab with chemotherapy reduce CBC risk. However, each adjuvant therapy regimen had a different impact on the CBC subtype distribution. Taxane-containing chemotherapy and aromatase inhibitors were associated with the largest CBC risk reduction

Adjuvant radiotherapy for primary breast cancer in BRCA1 and BRCA2 mutation carriers and risk of contralateral breast cancer with special attention to patients irradiated at younger age

The purpose of this study was to estimate the influence of adjuvant radiotherapy for primary breast cancer (BC) on the risk of contralateral BC (CBC) in BRCA1 or BRCA2(BRCA1/2) mutation carriers, with special attention to patients irradiated at age younger than 40 years. Additionally, tendencies in locoregional treatments and rates of contralateral risk-reducing mastectomy over time were explored. In this retrospective cohort study, 691 BRCA1/2-associated BC patients treated between 1980 and 2013 were followed from diagnosis until CBC or censoring event including ipsilateral BC recurrence, distant metastasis, contralateral risk-reducing mastectomy, other invasive cancer diagnosis, death, or loss to follow up. Hazard ratios (HR) for CBC associated with radiotherapy were estimated using Cox regression. Median follow-up time was 8.6 years [range 0.3–34.3 years]. No association between radiotherapy for primary BC and risk of CBC was found, neither in the total population (HR 0.82, 95 % CI 0.45–1.49) nor in the subgroup of patients younger than 40 years at primary diagnosis (HR 1.36, 95 % CI 0.60–3.09). During follow-up, the number of patients at risk decreased substantially since a large proportion of patients were censored after contralateral risk-reducing mastectomy or BC recurrence. Over the years, increasing preference for mastectomy without radiotherapy compared to breast-conserving surgery with radiotherapy was found ranging from less than 30 % in 1995 to almost 50 % after 2010. The rate of contralateral risk-reducing mastectomy increased over the years from less than 40 % in 1995 to more than 60 % after 2010. In this cohort of BRCA1/2-associated BC patients, no association between radiotherapy for primary BC and risk of CBC was observed in the total group, nor in the patients irradiated before the age of 40 years. The number of patients at risk after 10 and 15 years of follow-up, however, was too small to definitively exclude harmful effects of adjuvant radiotherapy

An App-Assisted Travel Survey in Official Statistics: Possibilities and Challenges

Advances in smartphone technology have allowed for individuals to have access to near-continuous location tracking at a very precise level. As the backbone of mobility research, the Travel Diary Study, has continued to offer decreasing response rates over the years, researchers are looking to these mobile devices to bridge the gap between self-report recall studies and a person's underlying travel behavior. This article details an open-source application that collects real-time location data which respondents may then annotate to provide a detailed travel diary. Results of the field test involving 674 participants are discussed, including technical performance, data quality and response rate

An App-Assisted Travel Survey in Official Statistics: Possibilities and Challenges

Advances in smartphone technology have allowed for individuals to have access to near-continuous location tracking at a very precise level. As the backbone of mobility research, the Travel Diary Study, has continued to offer decreasing response rates over the years, researchers are looking to these mobile devices to bridge the gap between self-report recall studies and a person’s underlying travel behavior. This article details an open-source application that collects real-time location data which respondents may then annotate to provide a detailed travel diary. Results of the field test involving 674 participants are discussed, including technical performance, data quality and response rate

Maximum interpolable gap length in missing smartphone-based GPS mobility data

Passively-generated location data have the potential to augment mobility and transportation research, as demonstrated by a decade of research. A common trait of these data is a high proportion of missingness. Naïve handling, including list-wise deletion of subjects or days, or linear interpolation across time gaps, has the potential to bias summary results. On the other hand, it is unfeasible to collect mobility data at frequencies high enough to reflect all possible movements. In this paper, we describe the relationship between the temporal and spatial aspects of these data gaps, and illustrate the impact on measures of interest in the field of mobility. We propose a method to deal with missing location data that combines a so-called top-down ratio segmentation method with simple linear interpolation. The linear interpolation imputes missing data. The segmentation method transforms the set of location points to a series of lines, called segments. The method is designed for relatively short gaps, but is evaluated also for longer gaps. We study the effect of our imputation method for the duration of missing data using a completely observed subset of observations from the 2018 Statistics Netherlands travel study. We find that long gaps demonstrate greater downward bias on travel distance, movement events and radius of gyration as compared to shorter but more frequent gaps. When the missingness is unrelated to travel behavior, total sparsity can reach levels of up to 20% with gap lengths of up to 10 min while maintaining a maximum 5% downward bias in the metrics of interest. Temporal aspects can increase these limits; sparsity occurring in the evening or night hours is less biasing due to fewer travel behaviors

An App-Assisted Travel Survey in Official Statistics: Possibilities and Challenges

Advances in smartphone technology have allowed for individuals to have access to near-continuous location tracking at a very precise level. As the backbone of mobility research, the Travel Diary Study, has continued to offer decreasing response rates over the years, researchers are looking to these mobile devices to bridge the gap between self-report recall studies and a person's underlying travel behavior. This article details an open-source application that collects real-time location data which respondents may then annotate to provide a detailed travel diary. Results of the field test involving 674 participants are discussed, including technical performance, data quality and response rate