Question

For each of the following situations, state which type of
sampling plan was used. Explain whether you think the sampling plan
would result in a biased sample.

a) You randomly sample 15 schools out of 50 elementary schools in
your city, and then select every student in those 15 schools to be
in your sample, for a total of 1500 students.

b) You randomly sample 1500 students across all 50 elementary schools in your city.

c) Out of the 50 schools in your city, 25 are from school district A and the other 25 from school district B. You randomly sample 750 students across schools from district A and 750 students across schools from district B.

d) From all 50 schools you select the first 1500 students by alphabetical order of last name to be in your sample.

Answer #1

a) You randomly sample 15 schools out of 50 elementary schools in your city, and then select every student in those 15 schools to be in your sample, for a total of 1500 students.

**- Cluster Sampling ( A group is chosen )**

**This is an unbiased method if cluster size is same else
biased**

b) You randomly sample 1500 students across all 50 elementary schools in your city.

**- Simple Random Sampling**

**This is an unbiased method**

c) Out of the 50 schools in your city, 25 are from school district A and the other 25 from school district B. You randomly sample 750 students across schools from district A and 750 students across schools from district B.

**- Stratified sampling ( Some out of a group are chosen
)**

**This is an unbiased method**

d) From all 50 schools you select the first 1500 students by alphabetical order of last name to be in your sample

**- Systematic / Preferential sampling**

**This is biased method**

Identify the sampling technique used to obtain a sample in each
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The average fifth grade enrollment in the city’s elementary schools
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A researcher is interested in maximum-security inmates. She
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solve the following and mark the correct statement.
i)
In which case could the sampling distribution of sample means
be expected to be normally distributed?
A) The parent population is skewed, the sample size is
20.
B) The parent population is jumbled, the sample size is
20
C) The parent population is jumbled, the sample size is
50.
D) The parent population is uniform, the sample size is
20.
ii)
Recent English test scores were approximately normally
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72 150 41 200 125 31 52
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b. c.
d. e.
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- a.
b. c.
d. e.
Every third dog at the clinic is checked for ticks.
- a.
...

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