Draw Conclusions from samples

1
Section 7.5

• Draw Conclusions from samples

2
Vocabulary

• Population is a group of people or objects that
  you want information about
• Sample is a subset of the population being
  studied

3
Types of samples

• Self-selected sample members of a population can
  volunteer to be in the sample
• Systematic sample a rule is used to select
  members of a population
• Convenience sample easy to reach members of a
  population are selected
• Random sample each member of a population has
  an equal chance of being selected

4
Unbiased vs Biased

• Unbiased sample is representative of the
  population you want information about.
• Biased sample a sample that over-represents the
  population or under represents part of the
  population

5
Population Mean

• The true mean of the entire population
• Comparison can be made from a sample population
  to the population

6
Margin of Error

• Gives a limit on how much the responses of the
  sample would differ from the responses of a
  population
• Formula Margin of error

7
Correlation Coefficient

• Denoted by the letter, r, is a number from -1 to
  1 that measures how well a line fits a set of
  data pairs (x,y).
• If r is near 1 the points lie close to a line
  with a positive slope.
• If r is near -1 the points lie close to a line
  with a negative slope.
• If r is near 0 the points do not lie close to
  any line.