Head And Tail Research Articles

Use of Probability in Statistics: A Study

Probability is commonly used by data scientists to model situations where experiments conducted during similar circumstances, yield different results. Probability allows data scientists to assess the certainty of outcomes of a particular study or experiment. An experiment is a planned study that is executed under controlled conditions. When a result is not already predetermined, the experiment is referred to as a chance experiment. Conducting a coin toss twice is an example of a chance experiment. Today’s data scientists need to have an understanding of the foundational concepts of probability theory including key concepts involving probability distribution, statistical significance, hypothesis testing and regression.

Conditional Probability in Machine Learning

To help teaching of machine learning course, manipulation rules and application examples of conditional probabilities in machine learning are presented. The emphasis is to make a clear distinction between reasonable assumptions and logical deductions developed from assumptions and axioms. The formula for conditional probability of conditional probability is presented with examples in Bayesian coin tossing, Bayesian linear regression, and Gaussian processes for regression and classification. The signal + noise model is formulated in terms of a proposition and exemplified by linear-Gaussian models and linear dynamical systems.

When knowledge hurts: humans are willing to receive pain for obtaining non-instrumental information

Humans and other animals value information that reduces uncertainty or leads to pleasurable anticipation, even if it cannot be used to gain tangible rewards or change outcomes. In exchange, they are willing to incur significant costs, sacrifice rewards or invest effort. We investigated whether human participants were also willing to endure pain—a highly salient and aversive cost—to obtain such information. Forty participants performed a computer-based task. On each trial, they observed a coin flip, with each side associated with different monetary rewards of varying magnitude. Participants could choose to endure a painful stimulus (low, moderate or high pain) to learn the outcome of the coin flip immediately. Importantly, regardless of their choice, winnings were always earned, rendering this information non-instrumental. Results showed that agents were willing to endure pain in exchange for information, with a lower likelihood of doing so as pain levels increased. Both higher average rewards and a larger variance between the two possible rewards independently increased the willingness to accept pain. Our results show that the intrinsic value of escaping uncertainty through non-instrumental information is sufficient to offset pain experiences, suggesting a shared mechanism through which these can be directly compared.

Random number generation using spontaneous symmetry breaking in a Kerr resonator.

We demonstrate an all-optical random number generator based on spontaneous symmetry breaking in a coherently driven Kerr resonator. Random bit sequences are generated by repeatedly tuning a control parameter across a symmetry-breaking bifurcation that enacts random selection between two possible steady-states of the system. Experiments are performed in a fiber ring resonator, where the two symmetry-broken steady-states are associated with orthogonal polarization modes. Detrimental biases due to system asymmetries are suppressed by leveraging a recently discovered self-symmetrization phenomenon that ensures the symmetry-breaking dynamics act as an unbiased coin toss, with a genuinely random selection between the two available steady-states. We optically generate bits at a rate of 3 MHz without post-processing and verify their randomness using the National Institute of Standards and Technology and Dieharder statistical test suites.

Diversity and inclusion for rodents: how animal ethics committees can help improve translation

Translation failure occurs when a treatment shown to be safe and effective in one type of population does not produce the same result in another. We are currently in a...

Mortality due to Multidrug-Resistant Gram-Negative Bacteremia in an Endemic Region: No Better than a Toss of a Coin.

The incidence of multidrug-resistant (MDR) bloodstream infections (BSIs) is associated with high morbidity and mortality. Little evidence exists regarding the epidemiology of BSIs and the use of appropriate empirical antimicrobial therapy in endemic regions. Novel diagnostic tests (RDTs) may facilitate and improve patient management. Data were assessed from patients with MDR Gram-negative bacteremia at a university tertiary hospital over a 12-month period. In total, 157 episodes of MDR Gram-negative BSI were included in the study. The overall mortality rate was 50.3%. Rapid molecular diagnostic tests were used in 94% of BSI episodes. In univariate analysis, age (OR 1.05 (95% CI 1.03, 1.08) p < 0.001), Charlson Comorbidity Index (OR 1.51 (95% CI 1.25, 1.83) p < 0.001), procalcitonin ≥ 1(OR 3.67 (CI 95% 1.73, 7.79) p < 0.001), and monotherapy with tigecycline (OR 3.64 (95% CI 1.13, 11.73) p = 0.030) were the only factors associated with increased overall mortality. Surprisingly, time to appropriate antimicrobial treatment had no impact on mortality. MDR pathogen isolation, other than Klebsiella pneumoniae and Acinetobacter baumanii, was associated with decreased mortality (OR 0.35 (95% CI 0.16, 0.79) p = 0.011). In multivariate analysis, the only significant factor for mortality was procalcitonin ≥ 1 (OR 2.84 (95% CI 1.13, 7.11) p = 0.025). In conclusion, in an endemic area, mortality rates in MDR BSI remain notable. High procalcitonin was the only variable that predicted death. The use of rapid diagnostics did not improve mortality rate.

An Optical Implementation of Quantum Bit Commitment Using Infinite-Dimensional Systems

Unconditionally secure quantum bit commitment (QBC) was widely believed to be impossible for more than two decades, but recently, based on an anomalous behavior found in quantum steering, we proposed a QBC protocol which can be unconditionally secure in principle. The protocol requires the use of infinite-dimensional systems, so it may seem less feasible in practice. Here, we propose a quantum optical method based on the Mach–Zehnder interferometer, which gives a very good approximation to such infinite-dimensional systems. Thus, it enables a proof-of-principle experimental implementation of our protocol, which can also serve as a practically secure QBC scheme. Other multi-party cryptographic protocols such as quantum coin tossing can be built upon it too. Our approach also reveals a relationship between infinity and non-locality, which may have an impact on the research of fundamental theories.

Cardiopulmonary Resuscitation

Cardiopulmonary Resuscitation

A pilot quasi-experimental controlled trial of a community-based, multilevel family planning intervention for couples in rural Uganda: evidence of feasibility, acceptability, and effect on contraceptive uptake among those with an unmet need for family planning

ObjectivesEffective interventions to reduce the unmet need for family planning in low-income settings are limited. This study aimed to establish the feasibility, acceptability, and preliminary effects of Family Health=Family Wealth (FH=FW), a multilevel intervention aimed to increase high-efficacy contraceptive uptake among couples wanting to delay pregnancy. Study designA pilot quasi-experimental controlled trial was conducted in rural Uganda, with 70 couples wanting to delay pregnancy but not using contraceptives (n = 140). Two matched clusters (communities) were randomly allocated to receive FH=FW or a comparator intervention via coin toss. FH=FW included health system strengthening elements and four facilitated group sessions. Interviewer-administered questionnaires were conducted at baseline and at ∼7-month and ∼10-month follow-up, and process data gathered feasibility/acceptability outcomes. ResultsOf 121 households visited in the intervention community, 63 couples were screened, and 35 enrolled. In the comparator, 61 households were visited, 45 couples screened, and 35 enrolled. Intervention attendance was 99%, fidelity was 96%, and 100% of participants reported being satisfied with the intervention. From no use at baseline, there was 31% more high efficacy contraceptive uptake at 7 months and 40% more at 10 months in intervention versus comparator couples (adjusted odds ratio = 1.68, 95% confidence interval = 0.78–3.62, p = 0.19). A decline in fertility desires was observed in intervention versus comparator participants from baseline (Wald χ2 = 9.87, p = 0.007; Cohen’s d: 7 months, 0.06; 10 months, 0.49). ConclusionsFH=FW is a feasible and acceptable intervention with strong promise in its effect on contraceptive uptake to be established in a future trial. ImplicationsThe FH=FW intervention addresses multilevel family planning barriers through four group dialogs with couples paired with efforts to reduce health system barriers. A quasi-experimental controlled trial provides preliminary support for its feasibility, acceptability, contraceptive uptake and fertility desire effects, and success in engaging both women and men.

Examining of crossover instructional strategy toward biology students’ academic performance in secondary schools

The study investigated how the crossover instructional strategy (CIS) affected secondary school students' biology academic performance in Onitsha Education zone. The non-randomized control group design, a quasi-experimental research strategy, was used in the study. A multi-stage sampling technique was used to choose 52 Senior Secondary Year Two (SS2) students (21 boys and 31 girls) from the 5,132 biology students in the zone. A coin toss was used to assign the sampled students, who were enrolled in two intact classes, to the control (10 males and 15 girls) or experimental (11 boys and 16 girls) groups at random. The researchers created a 50-item biology achievement test (BAT), which has a reliability coefficient of 0.81. The results demonstrated that CIS increased biology students' academic success more than the Conventional Lecture Method (CLM). Biology student academic achievement was unaffected by gender either alone or in combination with the teaching strategies. The research found that CIS is a cutting-edge educational strategy that actively involves students in the learning process in both formal and informal settings, helping them retain biology concepts and ultimately improve their academic performance. In accordance with the findings, the study recommended that biology teachers implement CIS in schools to improve students' biology achievement.

Thyroidectomy With or Without Nerve Identification: A Personal Experience and Technique.

Careful and precise dissection of the gland, away from the typical trajectory of the recurrent and external laryngeal nerves, poses a minimal or similar risk of nerve injuries compared to directly visualizing and identifying the nerves. In a randomized controlled study involving 150 patients with various thyroid disorders who underwent different surgical procedures (total, near total, and hemi thyroidectomy), the patients were randomly assigned into two groups using a coin toss. The first group (G1) consisted of 75 patients who underwent thyroidectomy with nerve visual identification, while the second group (G2) comprised 75 patients without the requirement of nerve visualization. The aim was to determine the method with a lower risk of complications. The incidence of external laryngeal nerve palsy (ELNP) was found to be higher in G1 patients compared to G2 patients (5.3% vs2%), while no cases of permanent recurrent laryngeal nerve (RLN) palsy were observed in either group. The frequency of total nerve injury was higher in G1, with 14 patients (10.2%), compared to G2, with eight patients (5.3%). However, there was no significant association between nerve identification and the rate of nerve injury (P value = 0.452). Among the different surgical procedures, total thyroidectomy for toxic goiter was the most common operation associated with transient external laryngeal nerve (TELN) injury and permanent external laryngeal nerve (PELN) injury. By employing meticulous dissection techniques in proximity to the thyroid capsule, experienced surgeons can effectively reduce the risk of nerve injury, even in the absence of direct nerve visualization.

Assessment of Bleeding Risk in Patients Being Considered for VTE Pharmacoprophylaxis in a Large Nationwide Cohort

More than 100,000 patients are hospitalized in the United States each day. Half of all venous thromboembolism (VTE) events occur in hospitalized patients. Hospital-related pulmonary embolism was declared the leading preventable cause of in-hospital death by the US Surgeon General, Centers for Disease Control and Prevention, and Centers for Medicare and Medicaid Services. Risk-stratification and targeted-prophylaxis are keys to prevention. Pharmacoprophylaxis is highly effective, though with an increased risk of bleeding. Therefore, decisions for VTE prophylaxis must balance the predicted risk of VTE against the predicted risk of bleeding in individual patients. While there are several risk assessment models (RAMs) to predict the risk of VTE, there are only two RAMs proposed to predict bleeding from pharmacoprophylaxis and neither has been validated in a large, unselected cohort of general hospitalized patients. We analyzed all consecutive unique hospital admissions of surgical and nonsurgical patients at all 1298 VA facilities nationwide between January 2016 and December 2021. IMPROVE and Consensus RAM scores were generated using data from a repository of the unified national VA electronic medical record. We assessed the predictive ability of the RAMs for bleeding within 30, 60, and 90 days after admission and compared their performance in surgical and nonsurgical patients by computing the areas under their respective receiver operating-characteristic curves (AUC). We analyzed 1,228,448 patients; 26.5% (n = 324,959) surgical and 73.5% (n = 903,489) nonsurgical. 68,372 (5.6%) patients had major bleeding (as defined by the International Society on Thrombosis and Hemostasis) within 90 days postadmission (surgical 5.0%, nonsurgical 5.8%). IMPROVE scores ranged from 0 to 22 (median, 3.5; interquartile range, 2.5-5.0); Consensus scores ranged from −5.60 to −1.21 (medina, −4.93; interquartile range, −5.60 to −4.93). Higher scores were associated with higher bleeding rates, however, the ability of either RAM to predict 90-day bleeding was no better than a coin toss (AUCs: IMPROVE, 0.61: Consensus, 0.59), and was similarly low at 30 and 60 days postadmission (Table). Both RAMs performed better in surgical vs nonsurgical patients (AUCs: IMPROVE, 0.64 vs 0.61; P < .001; Consensus, 0.63 vs 0.58; P < .001) (Figure). In this first known validation study evaluating existing RAMs for bleeding from pharmacoprophylaxis in an unselected cohort, increasing scores correlated with bleeding rates; though both RAMs had low predictive ability for major bleeding postadmission. Both RAMs predicted bleeding better in surgical vs nonsurgical patients, but the differences were of limited clinical importance. Further studies are urgently required to improve existing bleeding RAMs to facilitate systematic decision-making for VTE prophylaxis in hospitalized patients.TableArea under receiver operating characteristic curves (AUC) for the IMPROVE and Consensus Bleeding risk assessment models (RAMs) at different follow-up intervalsTime from hospital admission, daysImprove bleeding RAMConsensus bleeding RAMAUC (95% confidence intervals)P valueAUC (95% confidence intervals)P value0-300.62 (0.62-0.62)<.0010.61 (0.60-0.61)<.0010-600.62 (0.61-0.62).0720.60 (0.60-0.60).0120-900.61 (0.61-0.62)1.00(ref)0.59 (0.59-0.60)1.00(ref) Open table in a new tab

Investment Skill and Consistent Long-Term Alpha

How should an active investor calibrate their investment decisions, when the goal is to reach an outperformance target over the long term, without succumbing to large drawdowns in the interim? Closed-form expressions for the probability of consistent long-term alpha are derived and show that maximizing this probability requires a thoughtful calibration of skill, volatility, decision frequency, and costs. The article derives the minimum skill level for which the probability of consistent long-term alpha trends to its maximum for long investment horizons. This minimum skill level is not typically large, at only marginally above a fair coin toss. Unfortunately, the maximum probability of consistent long-term alpha is also not very large, even when skill is high and the investment horizon is long. The reason is that, although the probability of reaching the long-term goal rises with the time horizon for sufficiently high skill, so does the probability of experiencing the intertemporal loss that can force a stop-out in the interim.

Taming the Long Tail: The Gambler’s Fallacy in Intermittent Demand Management

Problem definition: “Long tail” products with intermittent demand often tie up valuable warehouse space and capital investment for many companies. Furthermore, the paucity of demand data poses additional challenges for model estimation and performance evaluation. Traditional inventory solutions are not designed for products with intermittent demand. In this paper, we propose a new framework to optimize the choice of “replenishment timing” and “replenishment quantity” for managing the inventory metrics of long tail products, when evaluated over a finite horizon. Methodology/results: Our analysis is motivated by a recent interesting observation that the gambler’s fallacy phenomenon actually holds in a finite number of coin tosses. We use this phenomenon to analyze the inventory problem for intermittent demand to demonstrate that classical inventory models using KPIs such as fill rate, average cost per cycle, or average cost per unit, etc., must necessarily “bias” the underlying demand distribution to account for the finite horizon effect. We provide the exact closed-form expressions of the biased distribution to account for this effect in performance evaluation. The results show that the choice of replenishment timing and replenishment quantity is essential to superior performance on several key inventory metrics. Managerial implications: For long tail products, the belief that it is less likely for another demand to arrive shortly after a preceding one (the gambler’s fallacy), turns out to be true when performance is tabulated over a finite horizon, even if demands across time are independent. So it pays to delay the replenishment of depleted stocks to save on holding cost and warehouse space. Managers can optimize the replenishment timing, besides choosing the replenishment quantity, to optimize the performance metrics of several classes of inventory problems. This is especially useful for companies managing a large number of long tail products. Funding: This work was supported in part by the National Natural Science Foundation of China [Grant 72192832] and the 2019 Academic Research Fund Tier 3 of the Ministry of Education-Singapore [Grant MOE-2019-T3-1-010]. Supplemental Material: The e-companion is available at https://doi.org/10.1287/msom.2023.1217 .

The Effect of Twelve-Week Karate and Salsa Dance Training on the Physical Fitness Performance of University Students

This study was performed to determine the effect of 12-weeks Karate and Salsa Dance training on the physical fitness performances of university students. A total of 124 students (age: 21.35 ± 1.59 year; height: 1.70 ± 0.08 cm; body weight: 67.1 ± 10.78 kg) have voluntarily participated in the study. The participants were divided into three groups using a random coin toss. The numbers of Karate group (KG), the Salsa Dance Group (SDG) and Control Group (COG) are 43 people (20 female, 23 male), 40 people (17 female, 23 male) and 41 people (12 female, 29 male), respectively. Technical training programs including two days a week and 90 minutes a day for 12 weeks were applied to the KG and SDG members accepting to the study. Body weight, height measurement, BMI calculation, bass stick balance test, handgrip strength test in upper and lower extremity strength measurements, wall squat leg strength test and plate tapping test for movement speed were performed to all participants before and after 12 weeks training. Since the data did not show normal distribution, Kruskal Wallis test was used in more than two groups and Mann Whitney-U test was used in binary comparisons. Looking at the results of KG and SDG, it was found that the BMI and muscle strength values of KG were better than the SDG values (p= .00). It was determined that the static balance values of SDG were higher than KG (p= 0.00). However, there was no significant difference between the movement speed of both groups (p&amp;gt; .05). All physical fitness parameters of both groups were found to be better than COG. We can suggest that sedentary individuals can benefit from karate technique training in gaining muscle strength. In addition, we can emphasize that it may be more appropriate to use salsa dance training in the development of static balance.

Karma and honest behavior: An experimental study

We examine the impact of karma beliefs on honest behavior. Previously studied strategies to promote honesty are either susceptible to rationalization or lack universality due to their religious ties. Karma, though rooted in religious contexts, is widely understood and accepted by secular society today. Its supernatural quality and simultaneous compatibility with atheism make it a widely appealing mechanism for prosocial behavior. Using two large online Prolific samples of US residents (N = 1,045 and N = 2,149), we test whether priming participants with karmic thoughts increases honesty in two anonymous online games: a coin toss where a “winning” outcome results in additional pay-out of $1, and a die roll where additional pay-out is determined according to the number on the die. We find that when there is a financial stake to winning, approximately 40% of participants lie completely in the coin toss and 11% of participants lie at least partially in the die roll. Furthermore, when partial lying is a possibility (die roll sample), we find that karmic nudges causally and significantly reduce dishonesty. Our results suggest that reminding people about karma has the potential to reduce people's propensity to cheat.

A million reasons or just one? How coin flips impact the number of relevant reasons for decisions

AbstractWhen individuals face difficult decisions, they may turn to random decision‐making aids, such as coin flips, for support. Here, we show that flipping a coin before making a decision impacts the number of reasons that individuals consider when making consumer choices (Study 1), policy decisions (Study 2), personal decisions (Study 3) and breakup decisions (Studies 4a, 4b, 4c). In Studies 1 to 3, flipping a coin resulted in fewer reasons or a reduced increase in the number of reasons that were deemed important. In contrast, when looking at qualitatively different decisions such as breakup decisions (4a to 4c), where using a coin flip may be perceived as unacceptable, flipping a coin resulted in more reasons being taken into account. Across studies, we show that flipping a coin impacts decision‐making processes. Taking breakup decisions aside, a coin flip may ease decision‐making by decreasing the number of reasons taken into account.

Experimental cheat-sensitive quantum weak coin flipping

As in modern communication networks, the security of quantum networks will rely on complex cryptographic tasks that are based on a handful of fundamental primitives. Weak coin flipping (WCF) is a significant such primitive which allows two mistrustful parties to agree on a random bit while they favor opposite outcomes. Remarkably, perfect information-theoretic security can be achieved in principle for quantum WCF. Here, we overcome conceptual and practical issues that have prevented the experimental demonstration of this primitive to date, and demonstrate how quantum resources can provide cheat sensitivity, whereby each party can detect a cheating opponent, and an honest party is never sanctioned. Such a property is not known to be classically achievable with information-theoretic security. Our experiment implements a refined, loss-tolerant version of a recently proposed theoretical protocol and exploits heralded single photons generated by spontaneous parametric down conversion, a carefully optimized linear optical interferometer including beam splitters with variable reflectivities and a fast optical switch for the verification step. High values of our protocol benchmarks are maintained for attenuation corresponding to several kilometers of telecom optical fiber.

Unconditionally secure quantum coin flipping

Quantum coin flipping (QCF) is an essential primitive for quantum cryptography. Unconditionally secure strong QCF with an arbitrarily small bias was widely believed to be impossible. But basing on a problem which cannot be solved without quantum algorithm, here we propose such a QCF protocol, and show how it manages to evade all existing no-go proofs on QCF.

Instruction effects on randomness in sequence generation.

Randomness is a fundamental property of human behavior. It occurs both in the form of intrinsic random variability, say when repetitions of a task yield slightly different behavioral outcomes, or in the form of explicit randomness, say when a person tries to avoid being predicted in a game of rock, paper and scissors. Randomness has frequently been studied using random sequence generation tasks (RSG). A key finding has been that humans are poor at deliberately producing random behavior. At the same time, it has been shown that people might be better randomizers if randomness is only an implicit (rather than an explicit) requirement of the task. We therefore hypothesized that randomization performance might vary with the exact instructions with which randomness is elicited. To test this, we acquired data from a large online sample (n = 388), where every participant made 1,000 binary choices based on one of the following instructions: choose either randomly, freely, irregularly, according to an imaginary coin toss or perform a perceptual guessing task. Our results show significant differences in randomness between the conditions as quantified by conditional entropy and estimated Markov order. The randomization scores were highest in the conditions where people were asked to be irregular or mentally simulate a random event (coin toss) thus yielding recommendations for future studies on randomization behavior.