STAT 305 COMPUTER LAB (JMP LAB)
1. The electric power, y, consumed each month by a chemical plant is thought to be related
to the average outside temperature, x1, and the tons of product produced, x2. The data for
last year are given below.
y304 290 259 240 250 280 316 300 275 250 275 300
x125 31 45 60 65 72 80 84 75 60 50 40
x2100 95 92 84 96 98 100 102 94 90 98 100
a) If you were using simple linear regression to predict y would you use x1 or x2? Justify your
answer.
b) Using the equation involving both x1 and x2 what output, y, would you predict for x1 = 60
and x2 = 97. Why you be reluctant to predict y for x1 = 60 and x2 = 102? (Construct a plot x1
versus x2 and use that plot to justify your answer.)
c) What equation would you use to estimate electric power consumed? Justify your answer.
d) Construct a histogram and box plot for the output, y.
e) Find the mean and standard deviation of y.
2. Data were collected on the compressive strength, y = c1, and splitting tensile strength, x =
c2, for 10 batches of concrete. A regression analysis was done using compressive
strength as the output and tensile strength as the input. Use the data below to answer the
following questions:
c1 = y
Comp
c2 = x
Tensile
1420 207
1950 233
2230 254
3000 328
3050 325
3070 302
2650 258
3110 335
2985 315
2870 302
a) Find the least squares line and the quadratic curve that fit these data.
b) What is the R2 when one does simple linear regression?
c) Would you use a quadratic fit for these data? Justify your answer.
d) On the scatter plot that includes the linear regression identify
ˆ
i i i
e y y
for the point (207,
1420).
