Performance of a bus depot. Refer to the International Journal of Engineering Science and Technology (February 2011) study of public bus depot performance, Exercise 9.23 (p. 508). Recall that 150 customers provided overall performance ratings at each of three different bus depots (Depot 1, Depot 2, and Depot 3). The average performance scores were determined to be significantly different at a = .05 using an ANOVA F-test. The sample mean performance scores were reported as x1 = 67.17, x2 = 58.95, and x3 = 44.49. The researchers employed the Bonferroni method to rank the three performance means using an experiment wise error rate of .05. Adjusted 95% confidence intervals for the differences between each pair of treatment means are shown in the table. Use this information to rank the mean performance scores at the three bus depots.
Performance of a bus depot. The performances of public bus depots in India were evaluated and ranked in the International Journal of Engineering Science and Technology (February 2011). A survey was administered to 150 customers selected randomly and independently at each of three different bus depots (Depot 1, Depot 2, and Depot 3); thus, the total sample consisted of 450 bus customers. Based on responses to 16 different items (e.g., bus punctuality, seat comfort, luggage service, etc.), a performance score (out of 100 total points) was calculated for each customer. The average performance scores were compared across the three bus depots using an analysis of variance. The ANOVA F-test resulted in a p-value of .0001.
a. Give details (experimental units, dependent variable, factor, treatments) on the experimental design utilized in this study.
b. The researchers concluded that the “mean customer performance scores differed across the three bus depots at a 95% confidence level.” Do you agree?
Plane of ecliptic Plane or Moon’s orbit—5 degrees tipped Intersection: Lines of Nodes Ascending node, descending node Crossing points where the two lines intersect and the Moon’s orbit passes through. Most full moons and new moons don’t result in eclipses because of this Phase measures only the angle away from Earth-Sun line At angles of 0 degrees and 180 degrees, you have “syzygy” Term sometimes also applied to alignments of Sun, Earth, and a planet North-South motion of Moon, i.e. the inclination of the plane of the lunar orbit wrt Earth’s orbit (ecliptic) is needed to understand… Orbital inclination adds North-South motion. Tilt ~5 degrees New moon near node Possible solar eclipse Full moon near node Possible lunar eclipse Lunar orbit “Precesses,” i.e. nodes move westward: “regression of the nodes” So “eclipse seasons” do not happen every 6 months but come a few days earlier each cycle Nodes complete rotation in ~18 2/3 years 360 degrees/18.7 years = ~19 degrees/year Or ~20 days/year = 10 days earlier each “season” 3x18 2/3 years = 56 years, so lunar eclipse patterns repeat pretty close to every 56 years. Stonehenge (Aubrey Holes) 56 “holes” might have marked events in lunar eclipse cycles Galileo, 1609 “Ashen Light” o Also called “earthshine,” “old moon in new moon’s arms” o Sunlight, twice reflected o Nearly new Moon means nearly full Earth More Coordinates: Equatorial Rotation of Earth: West to East o California follows New York Counter-clockwise as viewed from above North Pole o “right hand” rule Consider Mintaka, in Orion o Rises due East, sets due West o Traces celestial equator o Question: Where on Earth would you see it at the zenith Equatorial Coordinates 90 degrees north and south of celestial equator o North celestial pole (NCP) o South Celestial Pole (SCP) Celestial objects ascend daily in the east and descend in the west, paths centered on celestial poles If path crosses horizon, object will rise and set If close enough to the pose, it’s circumpolar. Review Motions of the Sun Annual solar motion o Earth orbits ccw viewed from North o Sun appears to shift eastward wrt stars o Sun’s eastward motion makes sidereal day 4 minutes shorter than solar day o Sun’s apparent annual motion (eastward) is opposite to apparent diurnal motion (westward) of stars. Lunar Eclipses Inclination of lunar orbit to ecliptic Don’t get one every full moon because it is not commonly at one of the nodes. Must occur at full moon Visible across the entire hemisphere, so more common in our experience than solar eclipses Umbra; penumbra Moon can be reddish in umbra Fun, nearly effortless to watch No longer scientifically important. o Used to be one of the few ways for astronomers to measure longitude on the earth.