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Introductory Statistics Practice Exam 1 Key Concepts

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Terms in this set (30)

  • What is a sample in statistics?
    A sample is defined as a subset of the population.
  • In left skewed data, how do the mean, median, and mode relate?
    The median is to the right of the mean, and the mean is to the left of the mode.
  • Population is to census as sample is to what?
    Population is to census as sample is to survey.
  • What is a precise measure?
    A precise measure is one where the random error is small.
  • What characterizes a discrete variable?
    A discrete variable has gaps in the values, such as number of people or cars.
  • Population is to parameter as sample is to what?
    Population is to parameter as sample is to statistic.
  • What is a blind experiment?
    An experiment where neither the subject nor the administrator knows the treatment is a blind experiment.
  • What are the two main types of data?
    Data can be qualitative or quantitative.
  • Give two examples of discrete variables.
    Examples of discrete variables: number of people in a classroom, number of cars.
  • Give two examples of continuous variables.
    Examples of continuous variables: height, age, length of time.
  • Difference between observational and experimental study?
    Observational studies measure without changing conditions; experimental studies apply treatments and include control groups.
  • Three characteristics of a well-designed experiment?
    • Control: control group to limit factors
    • Randomization: random sample selection to avoid bias
    • Replication: clear methods to reproduce results
  • Identify the sampling technique: selecting all students in 7 out of 11 districts.
    This is cluster sampling.
  • Identify the sampling technique: grouping students by district then randomly selecting from each group.
    This is stratified sampling.
  • Identify the sampling technique: assigning numbers to all students and randomly selecting individuals.
    This is simple random sampling.
  • Which measure of central tendency best represents skewed data?
    The median best represents the center because it is less affected by outliers than the mean.
  • True or False: Class width is the distance between lower and upper limits of a class.
    False. Class width is the difference between two consecutive lower limits.
  • True or False: The difference between two consecutive midpoints equals the class width.
    True.
  • True or False: The graph of cumulative frequencies should always decrease from left to right.
    False. It should increase from left to right.
  • True or False: Class boundaries ensure consecutive bars of a histogram touch.
    True.
  • True or False: The mean is most affected by outliers.
    True.
  • How to calculate weighted average price per unit sold?
    Use \(\bar{x}_w = \frac{\sum (price \times units)}{\sum units}\).
  • What is the cumulative frequency for 27.5 pounds in the male beagles ogive?
    About 41 beagles weigh 27.5 pounds or less.
  • What weight corresponds to a cumulative frequency of 45 beagles?
    Approximately 30.5 pounds.
  • How many beagles weigh between 22.5 and 29.5 pounds?
    About 36 beagles.
  • How many beagles weigh more than 30.5 pounds?
    About 10 beagles.
  • Which roller coaster height had the greatest frequency?
    Height of 125 feet had the greatest frequency.
  • How many roller coasters had a height of 72 feet?
    There were 14 roller coasters of 72 feet height.
  • How many classes are in the roller coaster frequency histogram?
    There are 6 classes.
  • What is the class width in the roller coaster histogram?
    Class width is approximately 53 feet.