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Latin
Latin/Greek Root Words
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(Statistics
connection) |
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AP Statistics Standards
III. Anticipating Patterns: (continued)
D.
Sampling distributions
8.
Chi-square distribution
IV. Statistical Inference:
B. Tests of significance
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Chi-square test for
goodness of fit, homogeneity of proportions, and independence (one-
and two-way tables)
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Essential Question:
Why would it be useful to have a
quantitative way to test if data fits a particular distribution
instead of merely relying on histograms, box plots, or normal
quantile plots? |
Ch. 13.1 Inference for Tables
- Name
2 instances when a chi-squared test can be used.
Note: chi is
pronounced kie (rhymes with pie).
- Goodness-of-fit
(tests the Ho that there is no difference between the distribution of sample data and a known distribution )
example
- Inference for 2-way
tables (tests the Ho that there is no
relationship between row and column variables)
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Describe the shape and
range of the chi-squared distribution.
Skewed right, zero to
positive infinity
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Determine degrees of freedom for a goodness-of-fit
chi squared calculation.
( df = n-1)
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Calculate the chi
squared statistic.
C2 =
S (O - E)2 / E
Where:
O = observed
data point
E = expected
- Perform chi squared goodness of fit hypothesis
tests.
Assumptions:
Simple
Random
Sample
Independence:
Observations are assumed to be
independent. Chi-squared can't be used to test correlated data
(like matched pairs or panel data).
- Note that the hypotheses for a chi-squared test
cannot readily be stated mathematically. They are as follows:
- Null hypothesis: The data's
distribution and the reference distribution are the same.
- Alternative hypothesis: The data's
distribution and the reference distribution are different.
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Find p-values for a chi squared test
using both the table and the TI - 83 calculator
Χ2 cdf ( LUD ).
Lower, Upper,
Degrees of freedom
Homefun: --
Read 11.1, Exercises 1, 3, 11, 13, 19, 21 pp.692 to 695
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Essential
Question: How
can statistics be applied to genetic analysis in the real world? |
- Describe how the
chi-squared test can be used for determining if a set of data is not
randomly distributed assuming that all events are equally probable.
Stats
Investigation: statistical
Analysis of Genome Data - computer lab using Minitab.
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Essential
Question: How
can tables containing massive amounts of data be rapidly screened
for relationships between the rows and columns? |
Ch. 13.2
Inference for Two-Way Tables
- Calculate expected
results for tables (p.720 ).
expected =
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(
row total ) ( column total ) |
(table total) |
- Calculate chi-squared
statistics for tables (p. 723).
- Determine the degrees
of freedom for a chi-squared (p. 724).
df = (rows-1)(columns-1)
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Perform hypothesis
tests using chi-squared statistics.
- Be able to read
chi-squared computer print outs.
Homefun: --
Read 11.2, Exercises 33, 35, 37, 43, 45, 51 pp. 725 to 729
Chapter 11 practice test multiple choice and free respnse, pp. 733 to 735 |
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