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Background NHS Blood and Transplant (NHSBT), the sole provider of blood to the National Health Service (NHS) in England, UK, must ensure a safe and sustainable supply of blood, whilst protecting donor health and wellbeing. Objectives The primary objective of this thesis is to advance the evidence base for strategies aimed at optimising donor iron status and improving the efficiency and sustainability of the blood supply through reduced deferrals and improved return rates. To achieve this objective, this thesis provides a portfolio of complementary quantitative epidemiological studies, which aimed to: (i) assess temporal trends and contemporary patterns in blood collection and adverse events; (ii) identify individual and collection site characteristics associated with return behaviour; (iii) characterise in detail the cross-sectional associations of the three optimal indices for defining iron deficiency (i.e., haemoglobin, ferritin, and soluble transferrin receptor [sTfR]), particularly modifiable and genetic correlates; (iv) develop and validate risk prediction models for low haemoglobin deferral to determine the added value of different types of data. In addition, the extent to which participants from blood donor research studies are representative of the national donor population will be investigated. This thesis will leverage large-scale, detailed, and multi-purpose data sources to overcome some of the limitations of previous studies, reporting findings to a greater detail than has previously been possible, in order to inform future studies that will directly influence blood donation practice and policy. Data sources Data extracts from the NHSBT national donor database (N=3,400,000) contained anonymised individual-level blood donation records from 2007-19 and were used to assess temporal trends and adverse events and to identify determinants of return behaviour, as well as to define comparator populations for the INTERVAL trial and COMPARE study for the purpose of assessing the representativeness of these cohorts. Data from the INTERVAL trial (2012-16; N=45,000), a large, parallel group, pragmatic, individually randomised trial, embedded in the routine blood service, evaluating the efficiency and safety of varying the frequency of whole blood donation over a 2-year period, was used to complement the analysis of return behaviour through study of adherence to assigned inter-donation intervals, in addition to contributing to the cross-sectional individual-participant data meta-analysis of correlates of iron levels and the development of risk prediction models for low haemoglobin deferral. Data from the COMPARE study (2016-17; N=30,000), a two-stage, systematic, within-person comparison diagnostic-accuracy study of different haemoglobin screening methods, contributed to the meta-analysis and was used to validate risk prediction models. The meta-analysis also included individual-participant data from the Cambridge BioResource (2007-9; N=7,500), Cambridge CardioResource (2010; N=2,500), and UK Blood Services Common Controls (2005; N=3,600). Study participants were well-characterised with extensive genetic, haematological, biochemical, lifestyle, health, and serially-assessed clinical information, in addition to routinely available demographic, donation history, and collection site characteristics, together with geographical and socioeconomic information through linkage to national datasets. Polygenic risk scores (PRSs) were derived for key iron measures using published variants. Results In analyses of over 20 million donor attendances, overall blood collection declined by 24∙1% between 2009 and 2018, but collection trends differed at a blood group level with targeted increases in the proportion of donations comprising universal, rare, and minor blood groups. As a result, the donor population contracted, shifting toward an older and more ethnically diverse population, comprising fewer male donors. Deferral for low haemoglobin increased substantially following the introduction of revised screening procedures in 2017, whilst adverse events remained stable. INTERVAL trial and COMPARE study participants were broadly representative of the national donor population of England, with only minor differences in age, sex, and number of previous donations. In analyses of return behaviour, during a 2-year follow-up period, 67·0% of donors from the national donor comparator population and 93·3% of participants from the INTERVAL trial returned to donate, with male sex, older age, number of previous attendances, and number of opportunities to donate positively associated with return. By contrast, non-white ethnicity, distance to the donation venue, deferral and adverse events at the previous visit were negatively associated with return. Substantial deviations from model assumptions revealed time-dependent associations. To reliably quantify cross-sectional associations of iron measures, individual-participant data on 85,847 whole blood donors from five relevant independent UK studies was harmonised to establish a large national consortium, allowing concomitant assessment of haemoglobin, ferritin, and sTfR. The iron measures shared some important modifiable risk factors, but the overlap was imperfect. In aggregate, only around one sixth of the total variation in haemoglobin and sTfR levels was explained by all of the variables considered, whereas, for ferritin levels, this was approximately one third for men and one quarter for women, of which the majority was attributable to factors describing donation frequency. Modifiable lifestyle characteristics (such as smoking, alcohol consumption, physical activity) and dietary habits together explained only a few percent of the total variation in iron measures. Notably, for haemoglobin, the respective PRS accounted for the largest fraction of the total explained variation. The prevalence of all stages of iron deficiency increased with higher donation frequency and younger age in women. 2∙1% of men and 6∙0% of women were deferred for low haemoglobin at their first donation attempt during the INTERVAL trial. The cross-validated concordance (C)-index of a prediction model for low haemoglobin deferral including conventional risk factors alone was 0·937 (95% CI 0·927 to 0·947) for men and 0·859 (0·847 to 0·871) for women, which could largely be attributed to the previous haemoglobin level. The inclusion of additional data types did not significantly augment the predictive ability of the model. Conclusions Differential trends by blood group highlight the increasing challenge for NHSBT of needing to reduce blood collection capacity to match declining overall demand and blood usage, whilst retaining donors of certain blood groups where demand is not falling. Perpetual large-scale population-based studies of temporal trends and contemporary patterns in blood collection and adverse events are needed to inform donor recruitment and retention strategies, and to prioritise research. Despite the INTERVAL trial and COMPARE study participants being broadly representative of the national donor population of England, the exact degree of generalisability remains somewhat uncertain. Key determinants of return behaviour were identified and point to possible opportunities for targeted retention strategies within the national donor population, as well as providing valuable information for the effective planning and delivery of short-term policies to allow more frequent donation. Evaluation of the correlates and possible determinants of iron measures has advanced understanding of the potential for prevention efforts to reduce the high prevalence of iron deficiency in whole blood donors to further safeguard donor health. Prediction models based on conventional risk factors alone provided accurate and reliable discrimination between those with low and acceptable haemoglobin levels at a subsequent donation attempt. Increased personalisation of blood donation, in the form of tailoring the inter-donation interval to the donor's capacity to give blood safely, may reduce the number of deferrals for low haemoglobin, which in turn may yield improvements in operational efficiency and enhance donor health, satisfaction, and retention.

Behavioral operations management (BOM) has gained popularity in the last two decades. The main theme in this new stream of research is to include the human behavior in Operations Management (OM) models to increase the effectiveness of such models. BOM is classified into 4 areas: cognitive psychology, social psychology, group dynamics and system dynamics (Bendoly et al. 2010). This dissertation will focus on the first class, namely cognitive psychology. Cognitive psychology is further classified into heuristics and biases. Tversky and Kahneman (1974) discussed 3 heuristics and 13 cognitive biases that usually face decision makers. This dissertation is going to study 6 cognitive biases under the representativeness heuristic. The model in this dissertation states that cognitive reflection of the individual (Frederick 2005) and training about cognitive biases in the form of warning (Kaufmann and Michel 2009) will help decisions’ makers make less biased decisions. The 6 cognitive biases investigated in this dissertation are insensitivity to prior probability, insensitivity to sample size, misconception of chance, insensitivity to predictability, the illusion of validity and misconception of regression. 6 scenarios in OM contexts have been used in this study. Each scenario corresponds to one cognitive bias. Experimental design has been used as the research tool. To see the impact of training, one group of the participants received the scenarios without training and the other group received them with training. The training consists of a brief description of the cognitive bias as well as an example of the cognitive bias. Cognitive reflection is operationalized using cognitive reflection test (CRT). The survey was distributed to students at University of North Texas (UNT). Logistic regression has been employed to analyze data. The research shows that participants show the cognitive biases proposed by Tversky and Kahneman. Moreover, CRT is significant factor to predict the cognitive bias in two scenarios. Finally, providing training in terms of warning helps participants to make more rational decisions in 4 scenarios. This means that although cognitive biases are inherent in the mind of people, management of corporations has the tool to educate its managers and professionals about such biases which helps companies make more rational decisions.

Marketers often give consumers samples of products before consumers make decisions. However, in the marketplace, samples can be offered in many different forms. For example, to promote a cake, marketers could provide a slice of the cake or a mini version of the cake. To advocate for a software package, marketers could provide either a trial version with full features but for a limited time only, or a trial version with limited features but for a longer time period. Are all samples created equal? While previous literature has mainly focused on the general effect of samples, in this dissertation I examine how different types of sampling experiences influence consumer responses to target products. Particularly, I focus on how representative samples are of their target products, as it relates to how fundamentally consumers recognize and understand products. Normatively, high representative samples (e.g., a mini cake) should be more effective than low representative samples (e.g., a slice of a cake) in promoting target products, as high representativeness eases perceived uncertainty about target products. However, counter-intuitively, across a series of online and field experiments, I find that low representative samples actually lead to more favorable responses to target products as compared to high representative samples. The effect of sample representativeness on consumer responses to target products is driven by a differential level of satiation – high representative samples lead to a higher level of satiation. Moreover, I find that the effect of sample representativeness on consumer responses to target products is strengthened when need for cognition is low.

Mediated intergroup contact can influence the way that we perceive others, particularly for individuals who have little contact with outgroup members. In fact, watching positive mediated interactions between ingroup and outgroup members can lead to improved attitudes toward the outgroup. However, interpersonal contact research has found that the extent to which an individual is seen as typical or representative of a group will influence changes in attitudes and stereotypes at the group level. Although a number of researchers have examined representativeness in interpersonal situations, few have explicitly tested this hypothesis in a mediated context. These studies have encountered issues when exploring representativeness that may be due to both a limitation in measurement and a confounding of representativeness with stereotypicality. The purpose of this dissertation is to create and test the Representativeness of Mediated Characters Scale (RMCS) in order to measure character representativeness. Presented here is a series of four studies aimed at exploring representativeness and its effects on positive attitude change. Study one focuses on the creation and validation of a representativeness scale built on previous research on typicality and interpersonal contact. Study two explores the factors that influence participants’ responses on the representativeness scale, including realism (of the mediated narrative), extent of prior contact with outgroup members, motivations to control prejudice, self efficacy, and attitudes toward outgroup members. Study three focuses on the relationship between representativeness and stereotypicality. Finally, study four involves an additional experiment to explore the effects of character representativeness on attitude change. Results show that the RMCS is a valid and reliable tool for measuring character representativeness. It is flexible enough to account for differences due to the style of the media portrayal and the previous life experience of the audience members. The results from study 3 suggest that representativeness (as measured by the RMCS) is unique from stereotypicality in many instances. In study 4, the results showed that the extent to which audience members believed that characters were representative of their group mediated the effects of media exposure on attitudes toward the outgroup. The more representative a character was, the more attitudes toward that character’s group were improved.

This study examines individual-level citizen participation in the notice and comment component of federal agency rulemaking. It focuses on characteristics of individual participants ascertained through a survey mailed to 400 actual commenters. Survey data is used to evaluate the representativeness of these participants to the general public. Also, the compatible of citizen participation in rulemaking with the democratic ideals of liberty, equality, and fairness is evaluated, along with potential consequences of proposed reforms.