Conference notes - "It's the Real Thing" Day 2

Tue, 23 Jun 2009 15:14:30 GMT

Maureen Fahey - “It’s the Real Thing” - day 2.

Median/median line.

Split the data into three parts. Take the average point of the outside thirds of the data and plot them. http://teachers.henrico.k12.va.us/math/HCPSAlgebra1/Documents/10-4/Finding%20Line%20of%20Best%20Fit.pdf

Quadratics
Government website - fuel economy vs. speed.

Ways to solve it:
-vertex form
-matrices (ax2+bx+c=y), use 3 points. If you have the y-intercept, you have c, and then it’s only a system of two equations (how is that?)
Doublechecked our curriculum - no mention of matrix/matrices.

Estat - statcan.gc.ca
http://www.statcan.gc.ca/estat/licence-eng.htm
Number of males registered in apprenticeship programs over the years - makes a lovely bowl-shaped quadratic.

There is US census data in Fathom. It’s hard to use it from the internet.

SAT vs. GPA data in Fathom. Interesting - correlation between high school GPA and first year GPA is only .3. Correlation between math SAT score and first-year GPA is only .15.

We’ll do one with both Fathom and Excel, to do a quadratic regression. Fathom doesn’t do quadratic regression very well - have to fake it out.

She says you can’t steal data that’s horizontal - show her “paste - transpose”.

Vertex form tells you the turning point of the data - at what point did they start treating the perinatal HIV cases differently?

In Fathom, make a variable called ‘calc’. Use “edit formula” to put in vertex form, using a slider called v1. Drag the ‘calc’ column onto the y axis along with the cases, and then when you use the slider, it shows you what the formula looks like. You don’t immediately see it - but when you make the slider negative, the parabola flips to face downwards the way you need it.

Prius Speed vs. MPG - interesting piecewise graph. http://www.metrompg.com/posts/speed-vs-mpg.htm

Piecewise functions on the calculator; divide by (x<43). Get the < sign by doing 2nd + test, then choosing relational function. When x<43, you get a 1, and it does nothing; but when x>43, you get 0, and it gives an error - does not draw the function at that point. Puts error in the table, which is okay.

(x>2 and x<4) does the same thing, for the middle piece. Get the “and” by 2nd+test, then over right to LOGIC.

Shipping data from LL Bean - good for piecewise, stepped data.
up to $25 3.95
25.01 to 50 5.95
etc.
Use an open dot at one end.

comments

kirstenn

Conference notes - "It's the Real Thing" Day 2