1,761,637 research outputs found
Manuscript: Robert B. Carnahan, Pittsburg May 1896
No full textTyped document, 2 pages, Carnahan, Pittsburg May '9
Traffic Fatalities and Injuries: The Effect of Changes in Infrastructure and Other Trends
No full textAn analysis of how various road infrastructure improvements affect traffic-related fatalities and injuries is conducted while controlling for other factors known to affect overall safety. The road infrastructure elements analysed include total lane miles, the fraction of lane miles in different road categories (interstates, arterial, and collector roads), the average number of lanes for each road category, and lane widths for arterials and collector roads. Other variables that are controlled for in the study include total population, population age cohorts, per capita income, per capita alcohol consumption, seat-belt legislation (and seat-belt usage), and a proxy variable that represents underlying changes in medical technology. The data used is a cross-sectional time series database of U.S. states and is analysed using a fixed effects negative binomial regression that accounts for heterogeneity in the data. Data from all 50 states over 14 years is used. Results strongly refute the hypothesis that infrastructure improvements have been effective at reducing total fatalities and injuries. While controlling for other effects it is found that demographic changes in age cohorts, increased seat-belt use, reduced alcohol consumption and increases in medical technology have accounted for a large share of overall reductions in fatalities.Peer reviewe
B63, Madison Project: Robert B. Davis Introducing Integers With Pebbles in the Bag (Presentation & classroom view), Grade 3-5, 1950s_1960s, Clip
No full textIn this 8 minutes whole class discussion about early algebra ideas (specifically with regards to integers), Researcher Robert B. Davis models adding positive and negative integers to a class of elementary school students by having the students add and remove stones from a bag. The actions involve one student giving a command “Go” and then a second student proposes the number of stones to be added or subtracted. Davis then responds to the children’s directions from the class by either adding or removing a specific number of stones to the bag based on the directions. Davis and the students describe each action with symbolic equations that designates addition as “adding more pebbles,” which they symbolize as ‘+’, and subtraction as “take away,” which they symbolize by ‘-‘ before the numeral to designate a negative number. Examples of the equations that the students construct to represent pebble actions are:
3-3=0
5-6=-1
4-1=+3
Toward the end of the session, using pebble actions, Davis leads the class to discuss the meaning of -3 and +3 using the expression 2-5. The whole class agrees that +3 means 3 more pebbles. The camera view focuses on the teacher and whole class.Robert B. Davis Institute for Learning. (1957). B63, Madison Project: Robert B. Davis Introducing Integers With Pebbles in the Bag (presentation & classroom view), Grade 3-5, 1957_1969, Clip. [video]. Retrieved fromTranscript is also availableStudents work not availabl
A34, Fraction problems: Sharing and Number Lines (presentation view), Grade 4, October 29, 1993, raw footage
No full textIn this raw footage, full-session video, Dr. Davis first introduces Gunnar Gjone as a visiting mathematics educator from Norway. The researcher, Carolyn Maher, begins the session by asking the students to review their conclusions from the previous day’s class when they were asked to share a candy bar equally among the students in their small group. Two groups had been composed of eight students while another was composed of nine students, and their task had been to determine how much more candy each person in the smaller group would receive than those in the larger group, which they agreed to be the difference between 1/4 and 1/9, after dividing each candy bar into 10 equal pieces. Based on Cuisenaire Rod models, the students concluded that the difference was 5/36. However, a number of students, including Meredith, still argued that the difference should be 1/5. After the class agrees that 5/36 is the difference, Jessica contends that the earlier distribution was not equitable. Andrew suggests that the 3 candy bars could be divided into 30 rectangular pieces (10 per candy bar) and shared evenly among all 25 students by having each student get one whole rectangular piece and 1/5 of one of the remaining 5 rectangular pieces. A whole-class discussion follows in which the students are asked to compare and order 1/2, 1/3, 1/4 and 1/5. David shares his solutions based on building models with Cuisenaire rods. Various students mark positions for each of these fractions, and also 1/10, on a number line segment from 0 to 1, drawn on an overhead transparency.The class is then asked to work in pairs to produce number line segments and mark the positions of unit fractions from 1/2 to 1/10 and also 1/100 and 1/1000. Several of the students, including Andrew and Jessica, located 1/3 at two different points on their number line. In a final class discussion, Alan shares his number line, which includes 1/100 and 1/1000, and contends that there could be three points for 1/3. The students discuss this and conclude that the same point on the line segment cannot be named both 1/3 and 2/3 or 1/3 and 3/3 although it is appropriate to name the same point 3/3 and 1.Robert B. Davis Institute for Learning. (1993). A34, Fraction problems: Sharing and Number Lines (presentation view), Grade 4, October 29, 1993, raw footage [video]. Retrieved fromA transcript is also available
A32, Fraction problems: Sharing and Number Lines (front view), Grade 4, October 29, 1993, raw footage
No full textIn this raw footage, full-session video, Dr. Davis first introduces Gunnar Gjone as a visiting mathematics educator from Norway. The researcher, Carolyn Maher, begins the session by asking the students to review their conclusions from the previous day’s class when they were asked to share a candy bar equally among the students in their small group. Two groups had been composed of eight students while another was composed of nine students, and their task had been to determine how much more candy each person in the smaller group would receive than those in the larger group, which they agreed to be the difference between 1/4 and 1/9, after dividing each candy bar into 10 equal pieces. Based on Cuisenaire Rod models, the students concluded that the difference was 5/36. However, a number of students, including Meredith, still argued that the difference should be 1/5. After the class agrees that 5/36 is the difference, Jessica contends that the earlier distribution was not equitable. Andrew suggests that the 3 candy bars could be divided into 30 rectangular pieces (10 per candy bar) and shared evenly among all 25 students by having each student get one whole rectangular piece and 1/5 of one of the remaining 5 rectangular pieces. A whole-class discussion follows in which the students are asked to compare and order 1/2, 1/3, 1/4 and 1/5. David shares his solutions based on building models with Cuisenaire rods. Various students mark positions for each of these fractions, and also 1/10, on a number line segment from 0 to 1, drawn on an overhead transparency.The class is then asked to work in pairs to produce number line segments and mark the positions of unit fractions from 1/2 to 1/10 and also 1/100 and 1/1000. Several of the students, including Andrew and Jessica, located 1/3 at two different points on their number line. In a final class discussion, Alan shares his number line, which includes 1/100 and 1/1000, and contends that there could be three points for 1/3. The students discuss this and conclude that the same point on the line segment cannot be named both 1/3 and 2/3 or 1/3 and 3/3 although it is appropriate to name the same point 3/3 and 1.Robert B. Davis Institute for Learning. (1993). A32, Fraction problems: Sharing and Number Lines (front view), Grade 4, October 29, 1993, raw footage [video]. Retrieved fromA transcript is also available
A33, Fraction problems: Sharing and Number Lines (side view), Grade 4, October 29, 1993, raw footage
No full textIn this raw footage, full-session video, Dr. Davis first introduces Gunnar Gjone as a visiting mathematics educator from Norway. The researcher, Carolyn Maher, begins the session by asking the students to review their conclusions from the previous day’s class when they were asked to share a candy bar equally among the students in their small group. Two groups had been composed of eight students while another was composed of nine students, and their task had been to determine how much more candy each person in the smaller group would receive than those in the larger group, which they agreed to be the difference between 1/4 and 1/9, after dividing each candy bar into 10 equal pieces. Based on Cuisenaire Rod models, the students concluded that the difference was 5/36. However, a number of students, including Meredith, still argued that the difference should be 1/5. After the class agrees that 5/36 is the difference, Jessica contends that the earlier distribution was not equitable. Andrew suggests that the 3 candy bars could be divided into 30 rectangular pieces (10 per candy bar) and shared evenly among all 25 students by having each student get one whole rectangular piece and 1/5 of one of the remaining 5 rectangular pieces. A whole-class discussion follows in which the students are asked to compare and order 1/2, 1/3, 1/4 and 1/5. David shares his solutions based on building models with Cuisenaire rods. Various students mark positions for each of these fractions, and also 1/10, on a number line segment from 0 to 1, drawn on an overhead transparency.The class is then asked to work in pairs to produce number line segments and mark the positions of unit fractions from 1/2 to 1/10 and also 1/100 and 1/1000. Several of the students, including Andrew and Jessica, located 1/3 at two different points on their number line. In a final class discussion, Alan shares his number line, which includes 1/100 and 1/1000, and contends that there could be three points for 1/3. The students discuss this and conclude that the same point on the line segment cannot be named both 1/3 and 2/3 or 1/3 and 3/3 although it is appropriate to name the same point 3/3 and 1.Robert B. Davis Institute for Learning. (1993). A33, Fraction problems: Sharing and Number Lines (side view), Grade 4, October 29, 1993, raw footage [video]. Retrieved fromA transcript is also available
B59,Stephanie and Dana-Classwork of the 5 tall-towers problem (Workview), Grade 4,Feb 6,1992-Raw footage
No full textAPA citation Robert B Davis Institute for Learning(B59),Combinatoric
V-mail Envelope, Robert B. Ray to Mrs. Robert B. Ray, October 31, 1944
No full textThis unfolded V-Mail envelope is addressed to Mrs. Robert B. Ray (Denise Beyt Ray) in Kosciusko, Mississippi from her husband, Lt. Col. Robert B. Ray at 9th General Hospital APO in San Francisco, California. The envelope is ink stamped that it is not suitable for filming and a red, six cent air mail postage stamp is in the upper right. The postmarks are not readable.https://scholarsjunction.msstate.edu/mss-webb-collection/1795/thumbnail.jp
Written Statement of Robert B. Willumstad
Full text linkWritten Statement of Robert B. Willumstad, Former Chief Executive Officer of the American International Group before the Congressional Oversight Pane
Bikesharing in Philadelphia: do lower-income areas generate trips?
No full textMany bikeshare programs seek to equitably serve residents from different income strata. Experience from other cities in the US and elsewhere in the developed world suggest that bikeshare systems are used mostly by more affluent populations. In order to encourage more bikeshare usage among low-income populations, the City of Philadelphia sited docking stations in low-income neighborhoods, allowed cash payments, and provided discounts to those receiving food-stamps. We examined one-year of data for Philadelphia’s Indego bikeshare system between April 2017 and March 2018. Travel patterns were examined and suggested that bikeshare trips taken from docking stations in lower-income areas are for work commute trips. Multivariate regression models confirmed that lower-income areas generate fewer trips while controlling for other factors such as transit access and whether the station is proximate to a bicycle lane. Our results suggest that despite Indego’s efforts, more work is needed to generate bikeshare trips in lower income neighborhoods.Peer reviewe
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