One portion of the research described in a paper by Yean-Jye Lu5 involved an evaluation of maneuver times for vehicles of various sizes that were involved in making a left turn at an intersection with a separate left-turn lane but without a separate left-turn phase on the traffic light governing the intersection (an “unprotected” left-turn maneuver). The maneuver time was measured from the instant that a vehicle entered the opposing lanes of traffic until it completely cleared the intersection. Four-cylinder automobiles were classified as “small cars” and sixor eight-cylinder automobiles as “large cars.” Trucks and buses were combined to form a third category identified as “truck or bus.” Other motorized vehicles (motorcycles, etc.) were ignored in the study. A summary of the data, giving maneuver times (in seconds) for vehicles that attempted the left-turn maneuver from a standing stop, appears in the accompanying table.
a Is there sufficient evidence to claim that the mean maneuver times differ for the three vehicle types? Give bounds for the attained significance level.
b Indicate the appropriate conclusion for an α = .05 level test.
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Mathematical Statistics with Applications
- The authors of a paper investigated whether water temperature was related to how far a salamander would swim and whether it would swim upstream or downstream. Data for 14 streams with different mean water temperatures where salamander larvae were released are given (approximated from a graph that appeared in the paper). The two variables of interest are x = mean water temperature (°C) and y = net directionality, which was defined as the difference in the relative frequency of the released salamander larvae moving upstream and the relative frequency of released salamander larvae moving downstream. A positive value of net directionality means a higher proportion were moving upstream than downstream. A negative value of net directionality means a higher proportion were moving downstream than upstream. Mean Temperature (x) Net Directionality (y) 6.12 −0.088.11 0.25 8.57 −0.1410.51 0.00 12.5 0.08 12.04 0.03 12.45 −0.0717.93 0.29 18.34 0.23 19.84 0.24 20.3 0.19 19.02 0.14 17.78 0.05 19.67…arrow_forwardA research study was conducted at a local college collecting data on the models (brands) of cars parked in the student parking lot. This type of data collected would be considered/described as Qualitative Data or Quantitative Data?arrow_forwardA study is conducted to determine the relationship between study hours and exam scores, what is the dependent variable in this scenario?arrow_forward
- Fish produce a hormone called isotocin, a hormone that is similar to oxytocin in mammals. Both hormones, oxytocin and isotocin, have been linked to social behaviors including the suppression of social anxiety, trust, and attachment. Prior to this study the relationship between isotocin in the bloodstream and the amount of aggression or submission individual cichlid fish display was unknown. The researchers hypothesized that isotocin would suppress aggressive behaviors in cichlids to promote social cohesion as these fish exist in large social groups (schools). To address this hypothesis each of 10 fish were exposed to two treatments 1 week apart. One at a time a fish was randomly selected from the group of 10 and either injected with a saline solution ( that served as the control) or with isotocin. After this injection the fish was returned to its group and the amount of aggressive and submissive behaviors the fish demonstrated was recorded for the next 10 minutes. One week later this…arrow_forwardFish produce a hormone called isotocin, a hormone that is similar to oxytocin in mammals. Both hormones, oxytocin and isotocin, have been linked to social behaviors including the suppression of social anxiety, trust, and attachment. Prior to this study the relationship between isotocin in the bloodstream and the amount of aggression or submission individual cichlid fish display was unknown. The researchers hypothesized that isotocin would suppress aggressive behaviors in cichlids to promote social cohesion as these fish exist in large social groups (schools). To address this hypothesis each of 10 fish were exposed to two treatments 1 week apart. One at a time a fish was randomly selected from the group of 10 and either injected with a saline solution ( that served as the control) or with isotocin. After this injection the fish was returned to its group and the amount of aggressive and submissive behaviors the fish demonstrated was recorded for the next 10 minutes. One week later this…arrow_forwardRead the following excerpt of an article published on psychologytoday.com: “Researchers found that about 40% of college students in their study binge drink (i.e., consuming 5 or more drinks in a short amount of time) and that the vast majority of campus sexual assaults are fueled by alcohol.” Identify the variables of interest and indicate which the independent is and which the dependent variable is. Identify the classification of the independent variable (discrete or continuous) and explain the reason for your choice. Discuss what measure of central tendency is the most appropriate for each variable (independent and dependent variable) making sure to explain why.arrow_forward
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