Untitled Quiz

Statistics

• Statistics is the science of collecting, analyzing, interpreting, and presenting data.
• Descriptive statistics organizes and summarizes information using graphs, charts, tables, and calculations of statistical measures.
• A population is a collection of individuals, items, or data considered for a statistical study.
• A finite population has a limited number of data, items, or individuals.
• An infinite population has an unlimited number of data, items, or individuals.
• A sample is a part of a population.
• Sample size is the number of elements in a sample.
• A parameter is a numerical quantity measuring an aspect of a population.
• A variable is a characteristic of interest concerning individual elements in a population or a sample.

Classification of Variables

• Qualitative variables describe qualities or characteristics, which can be further classified as:
  • Nominal: Categories with no inherent order (e.g., hair color, religion).
  • Ordinal: Categories with a meaningful order (e.g., level of education, customer satisfaction).
• Quantitative variables describe quantities and can be further classified as:
  • Discrete: Values that can only be whole numbers (e.g., number of children in a family, accidents per day).
  • Continuous: Values that can take on any value within a given range (e.g., height, weight, age).

Data Processing

• Constant: A numerical characteristic that does not change.
• Frequency table: A table displaying classes of variables along with related frequency, relative frequency, and percent frequency.
• Grouped data: Data organized into classes or intervals.
• Ungrouped data: Data that is not organized into classes or intervals.

Measures of Central Tendency

• Mean: The average of a set of values. For a sample, calculated by summing all values and dividing by the number of values; for grouped data, calculated from a frequency table (∑fx/∑f).
• Median: The middle value in a sorted dataset.
• Mode: The most frequent value in a dataset.

Measures of Dispersion

• Range: The difference between the maximum and minimum values in a dataset.
• Variance: A measure of how spread out the values are from the mean.
• Standard Deviation (σ ): The square root of the variance (a measure of the spread of the values about the mean.)

Other Important Concepts

• Quartiles: Values that divide a dataset into four equal parts (Q1, Q2, Q3).
• Deciles: Values that divide a dataset into ten equal parts.
• Percentiles: Values that divide a dataset into 100 equal parts.
• Mean Deviation (MD): The average absolute deviation of values from the mean.