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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
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Sampling distribution of a
sample proportion
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Sampling distribution of a
sample mean
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Central Limit Theorem
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Sampling distribution of a
difference between two independent sample proportions
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Sampling distribution of a
difference between two independent sample means
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Simulation of sampling
distributions
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Essential Question:
Can we describe the shape of a
distribution made up of many means from samples of the same size even without knowing
what the population's distribution's shape is like? |
Ch
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Describe the difference between a parameter and
a statistic and give examples.
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Explain the use of p and p-hat.
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Given a sampling distribution, explain its
meaning.
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Determine if a statistic is unbiased.
Unbiased: sampling distr. mean = pop. mean
- Compare variability to bias .
Essential Question:
Which is worse, variability or bias? |
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State how the variability of a statistic changes
relative to population size.
Population size has no effect
as long as the population size is significantly larger than the
sample size. By contrast, a larger
sample size
reduces variability.
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State which distribution typically has less variability, a
sampling distribution or the population distribution it is based
on? It's the sampling distribution.
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Calculate standard error.
(standard error) = (σ of sampling
distr.)
= (σ of population) / (n^0.5)
Homefun
(formative/summative assessment):
Read section
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Stats
Investigation: Central
Limit Theorem |
Purpose:
Does the variability in the sampling
distribution actually decrease as predicted by the central limit
theorem?.
Instructions: Go to
http://intuitor.com/statistics/CentralLim.html and read
the write up. Open the Central Limit Theorem Applet and
set the number of samples slider to its maximum (max=2010).
Run at least 10 simulations using a variety of sample sizes
from 1 to 100. From the sampling distribution plot, record the
sample size, standard deviation, and standard error.
Analysis 1: Make a
scatter plot of standard deviation vs. sample size. Perform
linear regression and power regression on the data in the
plot. Also make a residual plot for both forms of regression.
Analysis 2: Make a
second scatter plot of standard deviation vs. standard error.
Perform linear regression, report the r-square value, and make
a residual plot for this data.
Questions /Conclusions:
- Which regression equation
best fits the data in Analysis 1? Explain why?
- Explain the r-square value for the most appropriate
equation in analysis 1.
- What is the predicted equation in analysis 2 and how
does it compare to the regression equation.
- In analysis 2, what is the difference between the
standard deviation of the sampling distribution and the
standard error. Why do they have almost identical values?
- What is the difference between sample size and number of
samples. Describe how increasing them influences the
sampling distribution.
- What is the difference between the central limit theorem
and the law of large numbers.
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Ch 9
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Calculate the mean and
standard deviations of a binomial distribution for proportions.
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Compare the binomial
distributions for proportions to the binomial distributions for
counts.
Data Type |
Mean |
Std Dev |
count |
np |
[np(1 - p)]^0.5 |
proportions |
p |
[p(1 - p) /
n]^0.5 |
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State why the binomial
distribution is basically always a sampling distribution.
n represents the size of a sample drawn from a
population.
- State the three rules of
thumb which must be met before using the normal approximation of the
binomial distribution (pp. 506 & 507).
Note: on an AP Stats Exam, always demonstrate that these 3 rules
are met before using a normal distribution approximation of the mean.
population > 10n
np > 10
n(1-p) > 10
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State how the
central limit
theorem applies to sampling distributions.
Relevance:
The central limit Theorem is one of the 2 foundation stones that
statistics rests on, the other being the Law of Large Numbers.
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A
sampling distribution made up of a large number of samples will
have a mean very close to the population mean and a standard deviation
very close to (σ of population) / (n^0.5)
Homefun
(formative/summative assessment):
--
Read section
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