Stats Unit 7
value that describes a characteristic of a SAMPLE
statistic
x̄
sample mean symbol
S∨x
sample standard deviation symbol
p̂
sample proportion symbol
value that describes a characteristic of a POPULATION
parameter
µ
population mean symbol
σ
population standard deviation symbol
p
population proportion symbol
population: all 10 yr old boys
sample: 50 10 yr old boys included in the study
parameter of interest: 75th percentile of heights of all 10 yr old boys
statistic: 75th percentile of heights of 10 yr old boys in sample- 56 inches
A pediatrician wants to know the 75th percentile for the distribution of
heights of 10-year-old boys, so she takes a sample of 50 patients and
calculates that the 75th percentile in the sample is 56 inches.
, Identify the population, the sample, the parameter of interest, and the statistic in the
setting
different statistics
different samples can produce......
sample statistics (could be mean, median, etc)
[assess statistics by comparing them to ALL POSSIBLE statistics]
in a SAMPLING distribution, dots represent...
S- shape/modal
O- outliers
C- center
S- spread
how to describe a distribution
The sample medians are roughly symmetric and unimodal. The mean sample
median is about 6. The sample medians
have a range of 8. There don't seem to be any outliers.
example of SOCS
in one SRS of 5, the sample median was 2
Explain was a single dot (value=2) represents on a sampling distribution (examining
sample median)
A median of ___ or smaller occurred in only #
of the # trials. Because a sample median of ___ is unlikely (about __% by chance
alone), it does/doesn't provide convincing evidence that...
How to answer a suspicion question
parameter of a population
sample statistics are used to estimate...
the mean of its sampling distribution is equal to the parameter
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