IM 7.8.13 Lesson: What Makes a Good Sample?
Find the value of each quotient mentally.
Your teacher will assign you to work with either means or medians. A young artist has sold 10 paintings. Calculate the measure of center you were assigned for each of these samples:
The first two paintings she sold were for $50 and $350.
At a gallery show, she sold three paintings for $250, $400, and $1,200.
Her oil paintings have sold for $410, $400, and $375.
Here are the selling prices for all 10 of her paintings:
Calculate the measure of center you were assigned for all of the selling prices.$50 $200 $250 $275 $280 $350 $375 $400 $410 $1,200
Compare your answers with your partner. Were the measures of center for any of the samples close to the same measure of center for the population?
The price per pound of catfish at a fish market was recorded for 100 weeks.
Here are dot plots showing the population and three different samples from that population. What do you notice? What do you wonder?
If the goal is to have the sample represent the population, which of the samples would work best?
Which wouldn't work so well? Explain your reasoning.
When doing a statistical study, it is important to keep the goal of the study in mind. Representative samples give us the best information about the distribution of the population as a whole, but sometimes a representative sample won’t work for the goal of a study! For example, suppose you want to study how discrimination affects people in your town. Surveying a representative sample of people in your town would give information about how the population generally feels, but might miss some smaller groups. Describe a way you might choose a sample of people to address this question.
An online shopping company tracks how many items they sell in different categories during each month for a year. Three different auditors each take samples from that data. Use the samples to draw dot plots of what the population data might look like for the furniture and electronics categories.
Population
