Population and Sample, Bias, Measure of Central Tendency and

Population and Sample, Bias, Measure of Central Tendency and

Vocabulary

• Population-- is an ENTIRE group of people or objects.

• Sample--is a PART of the population

• Example: NAMS is a population and the 7th grade students are a sample from the population.

Multiple Choice

A market research company wants to conduct a survey of voters to find out which candidate will likely win the next local elections.

Which sample population will give the most accurate data

• a random sample of supporters of one of the candidates

• a random sample of middle school kids

• a random sample of all voters in the district

• a random sample of visitors at a museum

Multiple Select

A bookstore owner asks every fifth customer on a single day if he or she owns an e-book reader. Select the random samples of the population from the list. Check all that apply.

• Store Customers

• Book Lovers

• People who buy books

• Book Store Owners

• E-book Owners

Multiple Choice

• The second half likely contains the higher scores so the graph will change.

• The second half likely contains the lower scores so the graph will change.

• The graph will likely balance out with each bar being the same height.

• The graph will probably look very similar to the way it appears now.

Bias vs UNBias Samples

• A BIAS sample--does not represent the population as a whole and tends to lean towards a part of the population

• For a sample to be UNBIASED-- IT MUST

• It must represent the larger population

• be selected at random

• Large enough to provide accurate data

Multiple Choice

Which of the following is a biased sample of the houses in your neighborhood?

• 20 houses randomly selected from a complete directory

• 20 houses generated randomly by a computer program

• 20 houses randomly selected that have newspapers delivered

• 20 houses randomly selected from a map of the neighborhood

Multiple Choice

Which survey question is most likely to result in an unbiased sample?

• Which do you like better, delicious apples or boring oranges?

• Do you prefer apples, like I do, or oranges?

• Don't you prefer apples to oranges?

• Which do you prefer, apples or oranges?

Measures of Central Tendency

• Mean--Average-- Add all the data values together then divide the sum by the number of data points

• Median- The middle number. First order your data least to greatest and then find the CENTER number. If there are two middle numbers find the average of the two (add them together then divide by 2)

• Mode- Is the number that repeats the MOST. You can have no mode or more than one in some data

• Range- The greatest value subtracted by the least value in the data.

Finding Interquartile Range

• First find the median of the data and this will be Quartile 2

• Find the median of the lower part of the data and this is Quartile 1

• Next find the median of the upper part of the data and this is Quartile 3

• 
  

  Subtract Quartile 3 and Quartile 1 to find the Interquartile Range of the data

Multiple Choice

Using the following data what is the correct quartile break down?

2, 2, 3, 2, 7, 2, 1, 1, 3, 8

• Q1-2.5

  Q2- 4.5

  Q3--2

• Q1-2

  Q2-2

  Q3-3

Multiple Choice

Using the following data determine the correct quartiles

78, 79, 75, 76, 74

• Q1-78.5

  Q2-75

  Q3-75

• Q1-74.5

  Q2-76

  Q3-78.5

Open Ended

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