Stats

• What is a census in statistics?

  A census measures every member of a population.
• What are the advantages and disadvantages of conducting a census?

  Advantage: Accurate results; Disadvantage: Expensive and time-consuming.
• What are sampling units?

  Individuals of the population that may be sampled.
• What is a sampling frame?

  A list of sampling units.
• What is simple random sampling?

  It gives every member of the population the same chance of being selected.
• How can random sampling be conducted?

  Using a random number generator or lottery sampling.
• What is the advantage and disadvantage of random sampling?

  Advantage: Bias-free; Disadvantage: Requires a sampling frame.
• What is systematic sampling?

  It involves taking every kth unit from a population.
• How do you determine k in systematic sampling?

  By dividing the size of the population by the size of the sample.
• What is stratified sampling?

  It ensures the sample represents different groups (strata) of a population.
• What is the advantage of systematic sampling?

  It is quick to use.
• How do you calculate the sample size in stratified sampling?

  Divide the sample size by the population size and multiply by the size of each strata.
• What is quota sampling?

  It fills strata by an interviewer or researcher instead of random selection.
• What is the advantage and disadvantage of quota sampling?

  Advantage: No need for a sampling frame; Disadvantage: Potential bias.
• What is opportunity sampling?

  It involves selecting individuals who are available at the time of sampling.
• What are the advantages and disadvantages of opportunity sampling?

  Advantage: Easy and cheap; Disadvantage: Unlikely to be representative.
• What is qualitative data?

  Non-numerical data, usually descriptive like words or colors.
• What is quantitative data?

  Numerical data that can be either discrete or continuous.
• What does discrete data mean?

  Data that can take fixed values.
• What does continuous data mean?

  Data that can take any value in a particular range.
• What is the time frame for the large data set mentioned?

  Six months between May and October in 1987, 1990, and 2015.
• What is unique about Perth's seasons?

  Summer and winter are switched compared to the UK.
• What is special about Beijing's climate?

  It has extreme seasonal variations with hot summers and very cold winters.
• What is notable about Jacksonville's climate?

  It is warm year-round and prone to hurricanes.
• What does "tr" mean in rainfall data?

  Trace, meaning less than 0.05 millimeters of rain.
• What does "n/a" mean in data readings?

  Not available, indicating the reading cannot be used in a sample.
• How is cloud cover measured?

  In octaves, as discrete values from 0 to 8.
• How is maximum gust speed measured?

  In knots, where one knot is equivalent to 1.15 miles per hour.
• When did the great storm in the UK occur?

  On October 15th and 16th in 1987.
• What does "x bar" represent in statistics?

  The mean, calculated as the sum of x values divided by n.
• How do you find the position of the lower quartile (Q1) in listed data?

  Divide the number of pieces of data by four.
• How do you find the median in listed data?

  Divide the number of pieces of data by two.
• How do you find the position of the upper quartile (Q3) in listed data?

  Calculate three-quarters of the way along the data, or \( \frac{3n}{4} \).
• How do you find percentiles in data?

  Multiply the percentile by n, where n is the total number of data points.
• What is the formula for finding the mean in grouped data?

  The mean is calculated as \( \frac{\sum fx}{\sum f} \).
• What should you remember about calculating positions in grouped data?

  Use \( \frac{n}{4} \), \( \frac{n}{2} \), and \( \frac{3n}{4} \) for Q1, median, and Q3 respectively.
• How do you find the position of the 57th percentile?

  Calculate \( 0.57 \times n \).
• What is the formula to find the position of the lower quartile (Q1) in listed data?

  Q1 is found by dividing the number of pieces of data by four.
• How do you find the median in listed data?

  The median is found by dividing the number of pieces of data by two.
• What is the formula for finding the upper quartile (Q3) in listed data?

  Q3 is found by taking three quarters of the way along, which is three times the number of pieces of data divided by four.