Publications
Refereed Journal Articles
John T. & Chen P. “ℒ1-Limit of Trimmed Sums of Order Statistics from Location-Scale Distributions with Applications to Type-II Censored Data Analysis.” Communications in Statistics — Theory and Methods, Vol. 37(16), 2008. [DOI]
The ℒ1-limit of trimmed sums of order statistics from location-scale distributions satisfying certain assumptions is derived. Based on this limit, an approximation to the asymptotic variance of a Best-Asymptotic-Normal (BAN) estimator for the location parameter is developed. Associated formulae are derived for four location-scale distributions commonly used in lifetime data analysis. Applications are illustrated by applying the approximation to comparing location parameters and to selecting the population with the largest location parameter, using censored samples from location-scale populations.
John T. & Chen P. “Selection of the Best from Log-normal Populations Using Type-II Censored Data — Unknown σi2 Case.” Sequential Analysis, Vol. 25, 2006. [DOI]
The problem of selecting the best from k lognormal (μi, σi2) populations using type-II censored samples is considered. The selection parameter is taken to be a linear combination aμ + bσ2, since many quantities of interest associated with the lognormal distribution can be expressed in this form. Two-stage procedures are proposed for both the equal and unequal unknown variance cases. A discussion on the optimality of the procedures is included.
John T. & Chen P. “Log-normal Selection with Applications to Lifetime Data.” IEEE Transactions on Reliability, Vol. 55(1), 2006. [DOI]
Selection problems on k lognormal populations are considered when the variances are unequal, under both known and unknown cases. Selection based on linear functions of the location and scale parameters is addressed. For the unequal and unknown variance case, a two-stage Rinott-type asymptotic procedure is proposed. An asymptotic procedure is also proposed for parametric selection based on α-quantiles, with relevance to reliability and survival analysis. Simulation studies evaluate and compare the procedures; applications are demonstrated using examples from reliability and quality control.
Clinical & Applied Research
Marwaha S., Long C., John T.T., & Koloms K. “User Preference and Comparative Workflow Evaluation of a Next Generation Vital Signs Monitor Designed for a Low Acuity Setting.” In: Kalra J., Lightner N. (eds) Advances in Human Factors and Ergonomics in Healthcare and Medical Devices, AHFE 2020. Advances in Intelligent Systems and Computing, Vol. 1205. Springer, Cham. [DOI]
Multiparametric automated vital sign monitors are slowly becoming the standard in outpatient practice settings where users value solutions that provide efficiency and simplify their clinical workflows. In order to evaluate whether our new to market device would meet expectations and requirements of device design we designed a study to look at the use of our new device in these settings and thereby quantify usability, preference and acceptance by clinicians.
Neely J., Marwaha S., Brough S., & John T.T. “Impact of Single Sign-On Adoption in an Assessment Triage Unit: A Hospital’s Journey to Higher Efficiency.” Journal of Nursing Administration, Vol. 50(3), pp. 159–164, 2020. [DOI]
Background: Clinician time is a valuable and costly resource. In an age where computer and clinical application usage is increasing, the need for providers to remember multiple usernames and passwords is increasingly inefficient. Further complexity is added to clinical workflows if clinicians must log into smart devices frequently without a simple solution for access and data security. Objective: The purpose of this study was to measure the average time required and time savings when taking vital sign measurements using Single Sign-On (SSO) on electronic medical record–connected vital sign monitors versus using two-factor authentication. User satisfaction, system usability, workflow preference, and efficacy of deployment were also evaluated. Results: Analysis showed significance in time savings by adopting SSO. SSO had a positive impact on staff efficiency and was the preferred method versus the two-factor log-in.
Alpert B., Quinn D., Kinsley M., Whitaker T., & John T.T. “Accurate Blood Pressure During Patient Arm Movement: The Welch Allyn Connex Spot Monitor’s SureBP Algorithm.” Blood Pressure Monitoring, Vol. 24(1), pp. 42–44, 2019. [DOI]
Current blood pressure measurement guidelines specify patient requirements, including being still. Some populations of patients cannot comply. This study proposes the first protocol to assess blood pressure device accuracy in the presence of patient-induced motion. Forty healthy volunteers participated; the device tested was the Welch Allyn Connex Spot Monitor using the SureBP algorithm. The device recorded a reading on the first cycle in 37 participants and in all 40 with one repeat cycle in the remaining three. Results support the validity of the SureBP algorithm under motion conditions.
Manuscript in Preparation
John T., Jagannathan R., & Velu R. “A Test of Linear Beta Pricing When Error Covariance Matrix is Diagonal.” Manuscript in Preparation.
Referee Service
Discrete Event Dynamic Systems | Sequential Analysis | Simulation Modelling: Practice & Theory | Journal of Business Research
Selected Presentations
“Statistical/Data Science Methods in Clinical Research.” Invited presentation, Society of Clinical Research Associates, New York Chapter. [Slides]
Invited presentations, Society of Clinical Research Associates (NY Chapter): statistical methods for clinical researchers, 2013–2023; including invited lecture at SOCRA 24th Annual Conference, Denver, September 2015. [SOCRA 2015 Slides]
Invited talk, CNY Biotech Accelerator: Statistics, Sample Size & Data Methods, 2017. [Slides]
“Selection Procedures for Log-Location-Scale Distributions.” Guest Lecture, MAT 752, Syracuse University, October 2016. [Slides]
“Leveraging Primary Market Research Synchronized with Data Mining Models” and “Segmentation Methods.” International Conference on Business Data Mining & Workshop, C.R. Rao Institute of Mathematics & Statistics, University of Hyderabad, December 2008. [Conference Slides] [Workshop Slides]
Invited Chair, Session on Statistics, AMS-MAA Joint Meetings, Phoenix, 2004.