Mack Shelley

Dr. Mack Shelley

Department of Political Science, and Department of Statistics, Iowa State University, Ames, IA 50011, USA
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Research Focus & Metrics

Academic Career Length

39Years (1988-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 March 2013 in ReCALL
Verified
Journal Article
Closed access
PDF file
MGMaja Grgurović
Maja Grgurović
CCCarol A. Chapelle
Carol A. Chapelle
Mack ShelleyMack Shelley
Mack Shelley
With the aim of summarizing years of research comparing pedagogies for second/foreign language teaching supported with computer technology and pedagogy not-supported by computer technology, a meta-analysis was conducted of empirical research investigating language outcomes. Thirty-seven studies yielding 52 effect sizes were included, following a search of literature from 1970 to 2006 and screening of studies based on stated criteria. The differences in research designs required subdivision of studies, but overall results favored the technology-supported pedagogy, with a small, but positive and statistically significant effect size. Second/foreign language instruction supported by computer technology was found to be at least as effective as instruction without technology, and in studies using rigorous research designs the CALL groups outperformed the non-CALL groups. The analyses of instructional conditions, characteristics of participants, and conditions of the research design did not provide reliable results because of the small number of effect sizes representing each group. The meta-analysis results provide an empirically-based response to the questions of whether or not technology-supported pedagogies enhance language learning, and the process of conducting the meta-analysis pointed to areas in research methodology that would benefit from attention in future research.

1 December 2002 in Journal of Occupational and Environmental Medicine
Verified
Journal Article
Closed access
WFWarren D. Franke
Warren D. Franke
SRSandra L. Ramey
Sandra L. Ramey
Mack ShelleyMack Shelley
Mack Shelley
It is unclear to what extent law enforcement officers (LEOs) experience increased prevalence of cardiovascular disease (CVD; defined as coronary heart disease, myocardial infarction, angina, or stroke) and, if so, whether perceived stress affects this relationship. First, self-reported CVD risk factors among currently employed male LEOs from 9 states (n = 2818) were compared to CVD risk factors among similarly-aged males with similar incomes in the same states (n = 8046). Second, CVD prevalence was compared among LEOs (n = 1791) and similarly-aged males with similar incomes (n = 2575) from four of these states. Finally, among the LEOs only, the possible effect of perceived stress on the relationship between CVD prevalence and CVD risk factors was assessed. LEOs reported higher prevalence of hypertension, hypercholesterolemia, tobacco use, and elevated body mass index. CVD prevalence did not differ significantly between the LEO group and the general population (2.3% ± 15% versus 3.1% ± 17%;P = 0.095). In the LEO-only group, the best predictors of CVD were: time in the profession (OR = 1.07; 95% CI = 1.03–1.11), perceived stress (OR = 1.05; 95% CI = 1.00–1.10), and hypertension (OR = 0.33; 95% CI = 0.18–0.62). In the LEO-only group, perceived stress was associated with CVD (P = 0.008), and three CVD risk factors were significantly affected by perceived stress: cholesterol, hypertension, and physical activity. Perceived stress was affected by duration of time in the profession (P = 0.004), independent of an age effect (P = 0.353). Among susceptible officers, perceived stress may contribute to CVD directly and through potentiating several CVD risk factors.

1 April 2015 in Royal Society Open Science
Verified
Journal Article
Open access
JPJill D Pruetz
Jill D Pruetz
PBP. Bertolani
P. Bertolani
KOK. Boyer Ontl
K. Boyer Ontl
SLS. Lindshield
S. Lindshield
Mack ShelleyMack Shelley
Mack Shelley
EWE. G. Wessling
E. G. Wessling
For anthropologists, meat eating by primates like chimpanzees (Pan troglodytes) warrants examination given the emphasis on hunting in human evolutionary history. As referential models, apes provide insight into the evolution of hominin hunting, given their phylogenetic relatedness and challenges reconstructing extinct hominin behaviour from palaeoanthropological evidence. Among chimpanzees, adult males are usually the main hunters, capturing vertebrate prey by hand. Savannah chimpanzees (P. t. verus) at Fongoli, Sénégal are the only known non-human population that systematically hunts vertebrate prey with tools, making them an important source for hypotheses of early hominin behaviour based on analogy. Here, we test the hypothesis that sex and age patterns in tool-assisted hunting (n=308 cases) at Fongoli occur and differ from chimpanzees elsewhere, and we compare tool-assisted hunting to the overall hunting pattern. Males accounted for 70% of all captures but hunted with tools less than expected based on their representation on hunting days. Females accounted for most tool-assisted hunting. We propose that social tolerance at Fongoli, along with the tool-assisted hunting method, permits individuals other than adult males to capture and retain control of prey, which is uncommon for chimpanzees. We assert that tool-assisted hunting could have similarly been important for early hominins.

1 April 2003 in Journal of Safety Research
Verified
Journal Article
Closed access
AAAna Arboleda
Ana Arboleda
PMPaula C. Morrow
Paula C. Morrow
MCMichael R. Crum
Michael R. Crum
Mack ShelleyMack Shelley
Mack Shelley

27 March 2021 in Journal of Aging and Health
Verified
Journal Article
Closed access
PDF file
PLPeiyi Lu
Peiyi Lu
DKDexia Kong
Dexia Kong
Mack ShelleyMack Shelley
Mack Shelley
Objectives: This study investigated the predictors of risk perception and its effect on older adults’ preventive behavior and/or medical care avoidance during the COVID-19 pandemic. Methods: Older respondents (age >50 years) from the MIT COVID-19 Preventive Health Survey reported their social distancing, hand washing, mask wearing, and medical care avoidance between July and October 2020 (n = 4395). Structural equation models were used. Results: Significant predictors of higher risk perception were female gender, older age, poorer health, city residency, personally knowing someone who had COVID-19, and correct knowledge of vaccine/treatment. Higher risk perception was subsequently associated with higher frequency/probability of practicing preventive behavior and/or avoiding medical care. Knowledge had the strongest path coefficient with risk perception. Discussion: Disseminating correct information to older adults could help them evaluate infection risk accurately. Educational programs on the precautions implemented at clinical settings to ensure patient safety may encourage older adults to seek timely medical care.

4 June 2021 in Nutrients
Verified
Journal Article
Open access
PDF file
EDElizabeth D. Davitt
Elizabeth D. Davitt
Michelle HeerMichelle Heer
Michelle Heer
Donna M. WinhamDonna M. Winham
Donna M. Winham
SKSimon T. Knoblauch
Simon T. Knoblauch
Mack ShelleyMack Shelley
Mack Shelley
During COVID-19 restrictions in spring 2020, college students experienced closed dormitories and increased unemployment and many students moved in with their families. College students were vulnerable to food insecurity pre-pandemic and this study examined how the living situations and food security status changed for Midwestern university students due to COVID-19 restrictions. An email survey administered to Iowa State University students between the ages of 18 and 30 who physically attended campus prior to its closure produced 1434 responses. Students living with a parent or guardian increased by 44% and were less likely to experience food insecurity or less likely to work. They had lower stress and ate more home-cooked meals. Students living on their own had higher rates of food insecurity, greater stress, poorer health status, higher cooking self-efficacy, and worked more hours. Seventeen percent of all students were food insecure; related factors were non-White ethnicity, lower cooking self-efficacy, undergraduate status, receipt of financial aid, employment, stress, living in the same situation as before the campus closure, and consumption of more take-out or fast food. These individuals had more barriers to food access. Knowledge of these factors provide useful information to inform future support services for this population in similar conditions.