## Math & Stats Events: 2022 - 2023

### Math/Stat Table

**Every Monday from 12:00 - 1:30 pmValentine Terrace Room A - downstairs in Valentine Hall**

Math/Stat Table is an informal social time for students and faculty to get together and chat. There's no need to be majoring in Mathematics or Statistics; all are welcome. Please join us any time between noon and 1:30 pm on Mondays in Terrace Room A, in the basement of Valentine.

**Apply for nomination to the National Honor Society for Statistics!**

**Would you like to be nominated for Mu Sigma Rho, the National Honorary Society for Statistics?**

The purpose of Mu Sigma Rho is to promote and encourage scholarly activity in statistics and to recognize outstanding achievement among students in eligible academic institutions.

Grab a pdf copy of your unofficial transcripts from Workday and

**complete this form**

**by Tuesday, March 14**if you are interested in being nominated! Submissions will be accepted after that date but are not guaranteed to be processed in time for the nomination deadline of March 21.

To complete the nomination, we require your name, a US mailing address, an annotated copy of your unofficial transcripts, and your permission to forward your transcript to the BCASA Mu Sigma Rho committee, which would be kept confidential through their process.

**Upcoming Statistics and Data Science Colloquium:**

Rebecca Andridge, PhD, Associate Professor, The Ohio State University College of Public Health, Division of Biostatistics

**Problematic Polls and Suspect Surveys: Assessing the Potential for Selection Bias and Nonresponse Bias**

**Thursday, March 23rd, 4:30pm talk in SMudd 206, 4:00pm refreshments in SMudd 208**

Pre-election polls that missed the mark. COVID-19 vaccination surveys that drastically overestimated vaccine uptake. Accurately measuring public opinion and behavior is becoming more and more challenging with declining response rates and increased costs. One often overlooked possible explanation for inaccurate polling or questionable survey estimates is the possibility of non-ignorable nonresponse or non-ignorable sample selection, that is, that whether or not a person participates in a poll or survey is a function of characteristics the survey is trying to measure. For example, likely voters who support a particular candidate might be less likely to answer a telephone poll about voting intention, or adults who are “anti-vaccine” might be less likely to respond to a survey about the COVID-19 pandemic and its impact on their lives. In this talk I will describe using a statistical methodology called *proxy pattern-mixture models* to estimate the potential impact of nonignorable nonresponse or nonignorable selection in polls and surveys. The method will be motivated by and illustrated on a set of pre-election polls in “swing” states conducted by ABC and the Washington Post in 2020 as well as two very large internet-based probability surveys (Delphi-Facebook, Census Household Pulse) that drastically overestimated COVID-19 vaccine uptake in the U.S. in early 2021. I will describe the data and assumptions necessary to implement the method and discuss challenges unique to each application. My hope is that future polls and surveys could use this methodology to provide additional bounds on published estimates, especially when sample sizes are very large and traditional confidence intervals are very small.

Rebecca Andridge is an Associate Professor of Biostatistics at The Ohio State University College of Public Health. She conducts methodologic work in imputation methods for missing data, primarily in large-scale probability samples, and measures of selection bias for nonprobability samples. In particular, she works on methods for imputing data when missingness is driven by the missing values themselves (missing not at random). She collaborates with researchers across campus, including the Institute for Behavioral Medicine Research, the Nisonger Center for Excellence in Developmental Disabilities, and The OSU Comprehensive Cancer Center. She teaches introductory graduate and undergraduate biostatistics and won the College's Outstanding Teaching Award in 2011. She is a Fellow of the American Statistical Association and is an associate editor of the *Journal of Official Statistics* and the *Journal of Survey Statistics and Methodology*.

**Upcoming Math lectures: Ron Buckmire, Professor of Mathematics, Occidental College **

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**Public Lecture: **

**Monday March 27th, 5:00-6:00pm, Kirkpatrick Lecture Hall (Science Center)**

The Intersection of Mathematics and LGBT Identity is Not Empty

In this talk, I will discuss how LGBT identity and mathematics intersect personally, professionally and historically. The talk will include the ways that my identity as someone who is underrepresented in the mathematics community due to my race and sexual orientation has played a role in my professional trajectory in the academy. It will also provide a brief recounting of the 1990s origins of Spectra, an organization for LGBT mathematicians, which dates back to a courageous response by national mathematical organizations to passage of a Colorado anti-gay rights ballot measure in 1992.

The Intersection of Mathematics and LGBT Identity is Not Empty

**Mathematics Colloquium (for students, faculty, and staff):**

**Tuesday March 28th, 4:30-5:30pm, Seeley Mudd 206**

**Different Differences: A Primer on NSFD Methods For Solving Differential Equations**

From Calculus we know that a derivative of a function can be approximated using a difference quotient. There are different forms of the different quotient, such as the forward difference (most common), backward difference and centered difference (more accurate). In this talk I will discuss several different differences, specifically nonstandard finite differences (NFSD) that can be used to approximate the derivatives that appear in differential equations as a solution technique. Many NSFD schemes have been discovered and promoted by Ronald E. Mickens, an African-American Emeritus Professor of Physics at Clark Atlanta University who has written more than 300 research articles and a dozen books. I'll provide a number of examples of how NSFD schemes can be used to solve a wide variety of problems drawn from first-semester Calculus to elementary ordinary differential equations to advanced computational fluid dynamics.

**RSVP to Prof. Amanda Folsom afolsom@amherst.edu**for dinner* with the speaker on 3/27 or 3/28 following the talks. *Five College Students/Faculty/Staff are warmly invited.