Confidence Intervals – Proportion and One Mean
1
The term
sampling frame
refers to the group that actually had a chance to get into the sample. Ideally,
this is the same as the population of interest, but sometimes it isn’t. In the following situation, describe
the population, the sampling frame, the sample, the parameter of interest, and the statistic.
A Gallup Poll is done using random digit dialing to reach individuals in households with landline
telephones. The purpose is to estimate the proportion of U.S. adults who favor stronger gun control laws.
Onethousand persons are sampled, and 63% favor stronger gun control.
a. Population = all U.S. adults (note that this is becoming a potential problem as many adults 
primarily younger adults  no longer have land line phones but instead use cell phones.
b. Sampling frame = adults in the households with landline telephones
c. Parameter = proportion of U.S. adults favoring stronger gun control
d. Sample = the 1,000 surveyed
e. Statistic =63%, the sample percent
2
From the Data Sets folder o
pen the
Class Survey
data.
a. Since this is a class survey of stat200 students at PSU what do you believe is the best population that
this data represents?
Answers vary, but some examples are “All PSU undergraduate students at University Park”; “All PSU
undergraduate students at Penn State”; “All PSU Stat200 Students”.
The population would NOT be all
stat 200 students in our section(s) since this survey would not be a sample but instead the population as all
students took the survey
b. How is the class survey representative of that population?
The class is probably similar to these populations in makeup regarding percent that are female,
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 '08
 BARROSO,JOAOR
 Statistics, Normal Distribution

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