Math 151 , Day 32, Wednesday, April 17, 2002Hit reload to get current versionafter class

(If you didn't do it yet,  Jumping Jacks = 1, Sperry Topsider (red top) = 2
    Take a sample of size 4 from each,  record, return numbers.
    Keep track of which box; return numbers to right box.) Who put numbers back in the other box?  What to do?

 HW questions on CI's ?
We'll continue here, with 2-sided tests on Friday
Significance testing  Introduction Day31
2-sided (2-tailed) test:
H₀: "Null hypothesis" A claim or statement about the population we would like to show is NOT true.
      H₀: µ =1000 hrs.  (Average lightbulb life.)
H_a: "Alternative hypothesis" A claim or statement about the population we are trying to find evidence FOR.  A value either much bigger than or much smaller than the H₀ value is evidence against H₀ & for H_a.
      H_a:   µ  Not = 1000 hrs. (Quality control on assembly line--find if it is "off" either way.)
   Sample of size n = 25.  Population sigma = 150 hrs.  Suppose xbar = 940 hrs. z = (940-1000) ÷ (150/5) = -2

 P-value: We measure the probability of seeing something (again) as extreme as the observed value (or more so).
So you need to measure the P-value symmetrically both directions from the observed value--so the P value is double what it would be for a one-sided test.  P-value is approximately 5%; more precisely, 2·.0228 = .0456
Our test is just barely significant at the .05 level; it is significant at the .06 level, the .10 level.  It's not significant at the .02 level or "higher".

PreClass assignment Day 32 for  Day 33

Significance Tests. Activstats: Same as given on Day 29.  Continuing,  Page19-4 talks about one-and 2 sided hypotheses.  We won't be doing Type I and Type II error now, but they're good to know about. Moore Continue with pp334-337 (pp337-8 optional)  6.3 next.  We'll skip 6.4.

HW Day32  Read (& reread) Sec 6.2-pp318-334  When that's under control, continue.

from Moore Sketching xbars for H0, p-value  p. 323, 6.25 SSHA  6.26 Spending on housing Stating null and alternative hypotheses  p. 325 6.27, 28, 29, 30  Calculating p-value (one-sided), relating to Sig. level  p. 328, 6.31 and 32 (extending 6.25 and 26)  6.33 restating jargon With next assignment  Calculating p-value (one or two-sided), using z test statistic, relating to Sig. level  p. 333, 6.34 price reduc. on coffee   6.35 crankshafts true? Use your calculator to find the sample mean.   6.36 cola? Use your calculator to find the sample mean.

Read,  to discuss

Optional  (more practice)      Stating null and alternative hypotheses  p.340, 6.41,42  Calculating p-value (one or two-sided), using z test statistic, relating to Sig. level  p. 340 6.43 watered milk?