Module 11

When information is being gathered about a group, the entire group of objects, individuals, or events is called the population.  Because gathering information about each member of a large group can be difficult or impossible, researchers often study a part of the population, called a sample. 

The size of a sample and the way the sample is chosen can have an effect on whether the sample is representative of the population or not.  

One way that we can represent a random selection is to use number cubes (dice). 

A sample in which every person, object, or event has an equal chance of being selected is called a random sample.  A random sample is more likely to be representative of the entire population than other types of samples.  When a sample does not accurately represent the population, it is called a biased sample. 

Once you have selected a sample of the population, be sure that the data is gathered without bias. Make sure that the survey questions themselves do not sway people to respond in a certain way.  

-Would you like to waste the taxpayer’s money to build a frivolous skateboard park?

-Do you favor a new skateboard park?

-Studies have shown that having a safe place to go keeps kids out of trouble. Would you like to invest taxpayer’s money to build a skateboard park?

After obtaining a random sample of a population, you can make inferences about the population.  Random samples are usually representative and support valid inferences. 

Using the information from the random sample, you can create dot plots and box plots.  Both of these can help you make inferences about the population. 

You can use data based on a random sample, along with proportional reasoning, to make inferences or predictions about the population. 

We already talked about using number cubes (dice) to generate random samples.  Another way is to use a graphing calculator or online random number generator.  Just type random number generator into Google and they have some easy ones to use.  

Another way to choose random samples is to pull samples from a bag where pieces have been put to represent the population.