Montana State University Billings
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Item Propensity Score-Matching Methods for Observational Studies: An Application to Stat 216 Data(2016-04) Theobold, AllisonMany fields of science are faced with the inability to perform randomized experiments, but wish to have the ability to estimate a treatment effect and make causal inference. Propensity score matching is a method that can be used in observational studies to obtain unbiased estimates of the treatment effect. In this paper we consider the theory behind utilizing propensity score matching to obtain these such estimates, as well as explain how to implement propensity score matching in R using the Matching package for data from Montana State University’s Introductory Statistics curriculum.Item Bulk optical characterization of dissolved organic matter from semiarid wheat-based cropping systems(2017-11) Romero, Carlos M.; Engel, Richard E.; D'Andrilli, Juliana; Chen, Cheng-Sao; Zabinski, Catherine A.; Miller, Perry R.; Wallander, R.Dissolved organic matter (DOM) plays a critical role in the cycling of nutrients and long-term agricultural sustainability. The composition of DOM in soil is likely altered due to management, yet there is limited knowledge on the effect of long-term cropping on DOM chemical character. Here, we characterized water extractable DOM composition along a gradient of soil organic carbon (SOC) affected by differing cropping and tillage intensity in a semiarid climate of the northern Great Plains, USA. Soil samples (0–10, 10–20, 20–30 cm) were collected from conventional till-fallow winter wheat (Triticum aestivum L.; Ftill-W), no-till spring pea/oilseed-wheat (Pisum sativum L.; Pg/O-W), and no-till continuous wheat (W-W) fields, and analyzed using UV/Vis absorbance and excitation-emission matrix fluorescence spectroscopy. The concentration of DOM decreased with depth and was significantly greater (P < 0.05) under W-W or Pg/O-W than Ftill-W. The absorbance at 254 nm (Abs254), a proxy for DOM aromatic nature, indicated that aromaticity decreased with depth and lower biomass-C inputs (i.e. W-W ≥ Pg/O-W ≥ Ftill-W). Multidimensional parallel factor (PARAFAC) analysis revealed humic-like (C1, C2), monolignol-like (C3), and protein/tannin-like (C4) components with varying fluorescence intensities as a function of cropping system and soil depth. DOM humification, indicated by the humification index (HIX), increased significantly with depth (P < 0.05) and was higher for Ftill-W (2.95) than W-W (2.61) or Pg/O-W (2.28). Overall, DOM became depleted of plant-derived constituents and was enriched by more decomposed, condensed substances in Ftill-W, as compared to W-W or Pg/O-W soils. DOM composition is strongly affected by cropping intensity and such changes are important drivers controlling SOC accretion in arable soils.Item Leveraging Innovation in Family Startups: A Stewardship Approach(Academic OASIS, 2014) Mori, PatricioFamily firms are often criticized for failing to seek new ventures, being conservative and resisting change. On the other hand, researchers believe that certain characteristics in family relationship can foster strategic flexibility. Drawing on Stewardship theory, this paper, rather than arguing in favor or against family business innovation, takes a contingency approach and analyzes variables that may affect innovation in family startups and the conditions that leverage their family resources as competitive advantage. Specifically, this paper proposes that altruism, power concentration and their interaction affect strategic flexibility. It is also argued that family business with main founders high in altruism and low on power concentration can become more innovative than when the main founder is low in altruism and high in power concentration. Finally, it is suggested that the effect of altruism on strategic flexibility should be stronger in family business than in non-family business. Implications for theory and practice are derived.Item Diversity and Founder Power in Global Start-Up Teams: Implications for Strategic Consensus(Academic OASIS, 2013) Mori, PatricioDrawing on Attribution Theory, this paper argues that conditions at founding affect strategic consensus, and its evolution in Global Start ups. High Founder Power and Low Functional Diversity are hypothesized to produce a high level of Strategic consensus in the Global founding team. Time is hypothesized to moderate the relationship between Functional Diversity and Strategic Consensus and also the relationship between Founder Power and Strategic Consensus. Relative Experience and Relative Educational level of the most Powerful Founder are proposed as moderators of the relationship between Founder Power and Consensus. A model for Strategic Consensus in Global Startups is proposed.