Transcript S P Inv 2.4.pptx

Math CC7/8 – Be Prepared
On Desk:
Learning Log:
1. Pencil
2. Calculator
3. Math Journal
4. SP Learning Log
1. HW: p. 47 #15-17, #34-37
*read directions above #32
2. Finish Partner Quiz?
3. Friday – ½ Day, 10:25 Dismissal
– Internet Safety Assembly
Tasks for Today
• Finish Partner Quiz?
• Lesson 2.4 – What Sample Size to Use?
Summary of lesson 2.3 – Choosing Random Samples
We had many different random samples of 30
from the population of 100. (movies & sleep)
• Were our samples the same, or was there variance
amongst our samples?
• Do you think some samples were a better
representation of the population than others?
Conclusion:
• Sampling is a good technique in general, but it can
occasionally lead to drawing poor conclusions.
Materials needed:
• 10-section spinner (0-9)
• Labsheet 2.3 A (movie & sleep data – 100 students)
Adapted: Movie data only, same partners!
1. Spin to find student numbers
for sample of 5 students
2. Record their movie data
Student #
1.
2.
3.
4.
Spin to find student numbers
for sample of 10 students
Record their movie data
# of Movies
Student # # of Movies
1.
2.
3.
3.
4.
4.
5.
5.
6.
7.
8.
9.
10.
B.
1. Find the mean of each sample (5 and 10 and 30).
2. Record your groups statistics on the class chart.
(Labsheet 2.4F)
Labsheet
2.4A for line
plots of
means of 5,
10, and 30
• The means for samples of 5 should show considerable
variation.
• The means for samples of 10 should show less variation
than 5, but more than the means for samples of 30.
• The means for samples of 30 should cluster near the
population mean of about 4.
The larger the sample size from which the
means are drawn, the better the estimate of the
mean for the entire population.
With a sample size of 50, the mean number of
movies watched would show less variation than
the line plots of a size of 30. There would probably
be a more pronounced clustering around 4.
The variability drops as the sample size increases.
The characteristics of the sample become closer to
those of the population as a whole.