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Simply Surveying

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Key Term

Simple random sample

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snowflakeAllyson and Marissa are heading home on the school bus. School was closed three hours early due to snow! The weather forecast predicts 8 inches of accumulation before nightfall.


allysonAllyson: I bet Maryland gets more snow than any other state this winter!

marissaMarissa: I learned in history class that Maryland is called “Little America.” So, Maryland probably gets about the same amount of snow as the other states this winter.


Create and Analyze

Let’s take a look at this situation:

The girls go to Allyson’s home. They decide to do a survey of the different states to see how Maryland compares to the other states in the United States for average snowfall amounts. Marissa finds out that Maryland averages 20.6 inches per year.

The girls decide that researching the other 49 states for snowfall averages would take too long. They each create a different survey method for estimating the average snowfall amount per state.

  • Marissa decides to look at four states, one in the east (Virginia), one in the west (California), one in the north (North Dakota) and one in the south (Texas). She will find the mean snowfall amount for these four states and compare it to Maryland.
  • Allyson decides to find the mean snowfall amount for all of the northern states. She figures that the southern states rarely have snow and would therefore be outliers and adversely affect the data.

  • Allyson’s mother overhears the girls and offers a third method. She suggests the girls place the names of the 49 other states on separate slips of paper, shuffle the slips of paper, and choose ten states at random. Then, the girls find the mean snowfall amount for the ten chosen states.

Check Your Understanding

 

allysonAllyson: Oh, That is right! I forgot! We should perform a simple random sample of our population. This will provide us with a random collection of states that will more accurately represent all of the states in the United States.


 

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