STAT 200 Week 1 Homework Problems
1.1.4 To estimate the percentage of households in Connecticut which use fuel oil as a heating
source, a researcher collects information from 1000 Connecticut households about what fuel is
their heating source. State the individual, variable, population, sample, parameter, and statistic
Answer:
Population – Households in Conn.
Sample – 1000 households in Conn.
Variable – number of households in Conn. that use fuel oil as a heating source
Individual – households in Conn.
Parameter – percentage of households in Conn. that use fuel oil as a heating source
Statistics – percentage of 1000 households sampled in Conn. of which use fuel oil
1.1.8 The World Health Organization wishes to estimate the mean density of people per
square kilometer, they collect data on 56 countries. State the individual, variable, population,
sample, parameter, and statistic
Answer:
Individual – density of people per sq. kilometer of a country
Variable – density of people per sq. kilometer
Population – people per sq. kilometer in all 56 countries
Sample – 56 countries to collect data from
Parameter – mean density per sq. kilometer for all countries
Statistic – mean density per sq. kilometer from the sample of 56 countries
1.2.4 You wish to determine the GPA of students at your school. Describe what process you
would go through to collect a sample if you use a stratified sample.
Answer:
If I were to collect a stratified sample of student’s GPA from my school, I would start
with creating subgroups. Next, I would pull from each subgroup random students and collect
overall GPA’s.
1.3.4 To evaluate whether a new fertilizer improves plant growth more than the old fertilizer, the
fertilizer developer gives some plants the new fertilizer and others the old fertilizer. Is this an
observation or an experiment? Why?
Answer:
In an observational study, researchers observe subjects and measure variables of interest
without assigning treatments to the subjects. The treatment that each subject receives is
determined beyond the control of the investigator while in an experiment, investigators apply
treatments to experimental units (people, animals, plots of land, etc.) and then proceed to observe
the effect of the treatments on the experimental units. Thus, the given problem of applying new
and old fertilizers to certain plants to evaluate whether the new fertilizer improves plant growth
more than the old fertilizer is obviously an experimental study.
1.1.4 To estimate the percentage of households in Connecticut which use fuel oil as a heating
source, a researcher collects information from 1000 Connecticut households about what fuel is
their heating source. State the individual, variable, population, sample, parameter, and statistic
Answer:
Population – Households in Conn.
Sample – 1000 households in Conn.
Variable – number of households in Conn. that use fuel oil as a heating source
Individual – households in Conn.
Parameter – percentage of households in Conn. that use fuel oil as a heating source
Statistics – percentage of 1000 households sampled in Conn. of which use fuel oil
1.1.8 The World Health Organization wishes to estimate the mean density of people per
square kilometer, they collect data on 56 countries. State the individual, variable, population,
sample, parameter, and statistic
Answer:
Individual – density of people per sq. kilometer of a country
Variable – density of people per sq. kilometer
Population – people per sq. kilometer in all 56 countries
Sample – 56 countries to collect data from
Parameter – mean density per sq. kilometer for all countries
Statistic – mean density per sq. kilometer from the sample of 56 countries
1.2.4 You wish to determine the GPA of students at your school. Describe what process you
would go through to collect a sample if you use a stratified sample.
Answer:
If I were to collect a stratified sample of student’s GPA from my school, I would start
with creating subgroups. Next, I would pull from each subgroup random students and collect
overall GPA’s.
1.3.4 To evaluate whether a new fertilizer improves plant growth more than the old fertilizer, the
fertilizer developer gives some plants the new fertilizer and others the old fertilizer. Is this an
observation or an experiment? Why?
Answer:
In an observational study, researchers observe subjects and measure variables of interest
without assigning treatments to the subjects. The treatment that each subject receives is
determined beyond the control of the investigator while in an experiment, investigators apply
treatments to experimental units (people, animals, plots of land, etc.) and then proceed to observe
the effect of the treatments on the experimental units. Thus, the given problem of applying new
and old fertilizers to certain plants to evaluate whether the new fertilizer improves plant growth
more than the old fertilizer is obviously an experimental study.
