Contexts in Which Best and Worst CBC are Most Valuable: Application to School Choice Joel Huber: Duke University Namika Sagara: Duke University Angelyn Fairchild: Research Triangle Institute

Why Study School Choice? School choice is an increasingly difficult reality for parents. It is possible to mimic aspects of the actual choices There are many analyses of actual school choices but few published conjoint studies Positive and negative reaction to features makes school choice ideal for Best/Worst choice based conjoint

Our process Identified attributes differentiating public schools in actual choices Pretested these to make sure we covered the most important ones with 4 continuous attributes and 4 binary ones Built a fixed B/W CBC design Ran the study on a national sample of 150 parents with a child entering grades 6-11.

Our Sample Sample: Parent of a child age 11 to 17 attending public school – 57% Female – 59% Caucasian – 59% had at least some college – Median income was between $50,001 and $75,000 “Think about your youngest child that is more than 11 years old.” – Age and gender – School grade – Select five important characteristics for child’s school (e.g., close to home)

An Important One-time Decision “Suppose you just moved to a new area where families are able to choose which school they would most like their children to attend.” Introduction to attributes and practice questions – We defined ranges of each attribute and asked relative importance – We built up gradually to more complex, realistic choices

Ultimate choice task

Attribute 1: Distance Travel time to school Bus Ride5 min15 min30 min45 min “About how many minutes does it take for your child to get to school now?”

Attribute 2: Academic Quality School Attributes Travel time5 min15 min30 min45 min % under Grade Level 15%25%35%45% “At your child's current school, what percent do you think are below grade level?”

Warm up Choice 1 “Next we will ask you to choose between two schools with different travel time and percent of students below grade level. Imagine that only two school options are available for your child, and the schools are the same except for the differences shown below.”

Attribute 3: Income School Attributes Travel time5 min15 min30 min45 min % under Grade Level 15%25%35%45% % Economically Disadvantaged 10%30%50%70% “At your child’s current school, what percent of students are economically disadvantaged?”

Attribute 4: Diversity School Attributes Travel time5 min15 min30 min45 min % under Grade Level 15%25%35%45% % Economically Disadvantaged 10%30%50%70% Percent Minority 25%40%55%70% “At your child's current school, about what percent of students are minorities?”

Warm up Question 2

Featured Programs International Baccalaureate (IB) Program

Featured Programs International Baccalaureate (IB) Program Science, Technology, Engineering and Math (S.T.E.M)

Featured Programs International Baccalaureate (IB) Program Science, Technology, Engineering and Math (S.T.E.M) Expanded Arts Program

Featured Programs International Baccalaureate (IB) Program Science, Technology, Engineering and Math (S.T.E.M) Expanded Arts Program Promote Sports Teams

One of 8 Best/Worst Choice Tasks

“Best” Schools % Economically Disadvantaged

“Worst” Schools % Below Grade Level Travel Time Arts % Economically Disadvantaged SportsSTEMIB % Minority

What is important in a school? Academic quality Travel time Income % Minority Arts STEM Sports

What is important in a School? Academic quality Travel time Income % Minority Sports IB Arts STEM

Who cares? Academic quality Travel time Income % Minority Sports IB Arts STEM Educated Parent Nonwhite Older child Lower income Part time

Who cares? Academic quality Travel time Income % Minority Sports IB Arts STEM Educated Parent Nonwhite Older child Lower income Part time Employed full time Higher income Younger Child White Less educated parent

What we learned By building complexity gradually it is possible to generate reliable responses for a difficult and important choice 8 choices is sufficient to separate those with quite different values B/W provides both insight into what is desired and feared, and generates stable individual estimates

Simple individual level estimation All the analysis used standard Sawtooth Software HB analysis Can we generate a simplified model that can allow feedback to subjects on the fly? Concert 4-level variables to linear, producing 4 linear, 4 binary variables from 8 Best and 8 Worst choices This follows from work by Saigal and Dahan (Sawtooth Software Proceedings 2012)

Individual Linear Choice Using Simple Vector Product Choice vector Y has 32 items, 4 for each choice set, code Best as a 1, Worst as -1 and Zero otherwise Design matrix X(32,8) is zero centered within each choice set B-hat = (X’X) -1 X’Y Since we use a fixed design X we multiply (X’X) -1 X’ (8 x32) by Y(32x1) to get B(8x1)

Correlation between HB and linear choice model

Correlation of HB and Linear with Self Explicated

Effective use of Best/Worst Choice Based Conjoint Best/Worst is appropriate for choices with levels people avoid or fear Where there is both attraction and avoidance, combining Best + Worst choices results in better results Analyzing Best + Worst with a linear model generates results reasonably close to HB analysis

Thank you!

What is important in a school? Academic quality Travel time Income % Minority Sports IB Arts STEM

Correspondence between HB and linear estimates HB Importance Estimates