STAT

• Statistics


  A science that studies data, involving processes from collecting, processing, analyzing, interpreting and communicating data
• Data


  A collection of facts from experiments, observations, sample surveys and censuses, and administrative reporting systems
• Frequency


  The number of times a particular data value occurs
• Variable


  Any characteristic, number, or quantity that can be measured or counted
• Population


  A collection of all elements under consideration in a statistical study
• Sample


  A part or a subset of the population from which the information is collected
• A manufacturer of kerosene heaters wants to determine if customers are satisfied with the performance of their heaters. Toward this goal, 5,000 of his 20,000 customers are contacted and each is asked," Are you satisfied with performance of the kerosene heater you purchased?"
• Qualitative variables


  Also called categorical variables, examples include sex, marital status, ethnicity and educational attainment
• Quantitative variables


  Also called numerical variables, examples include age, grades, income and time spent on paid or unpaid activities
• Classification of variables


  • Qualitative variable - a variable that yields categorical responses
  • Quantitative variable - a variable that takes on numerical values representing an amount or quantity
• Discrete variable


  A variable that can be counted, examples include the number of days for cellphones to fail, the ages of survey respondents measured to the nearest year, and the number of patients in a hospital
• Continuous variable


  A variable that can be measured, examples include the exact height of a survey respondent and the exact volume of some liquid substance, weight, length
• Levels of measurement


  • Nominal - a variable that does not have any evaluative distinction, one value is not greater than another
  • Ordinal - a variable that has an evaluative connotation, one value is greater or larger or better than the other
  • Interval - a variable that gives information about more or betterness as ordinal scales do, but interval variables have an equal distance between each value
  • Ratio - a variable that has the same properties as an interval scale except there is an absolute zero point
• Dependent variable


  A factor, property, characteristics or attribute that is measured and made the object of analysis
• Independent variable


  A factor, property, attribute, characteristic or approach that is introduced, manipulated or treated to determine if it influenced or causes change on the dependent variable
• Sample problem 1: Can the number of customers and price increase be used to predict weekly sales?
• Sample problem 2: Can consumer's perceptions of quality be determined by their perceptions of prices, brand image, and brand attitudes?
• Descriptive statistics


  The analysis of data that helps describe, show or summarize data in a meaningful way, but does not allow us to make conclusions beyond the data we have analyzed or reach conclusions regarding any hypotheses we might have made
• Sample problems for descriptive statistics application: What is the monthly allowance of all the students of ABC University? What are the political views of the youth in the urban areas with respect to inflation rate in Southeast Asia? What are the possible risks encountered in purchasing a life insurance as perceived by policy holders?
• Inferential statistics


  Methods concerned with making predictions or inferences about a larger set of data using only the information gathered from a subset of this larger set
• Sample problems for inferential statistics application: Is there a significant difference between the performance of U.E. graduates in the October CPA board examination and May CPA board examination? Is there a significant difference in the performance of students when classified according sex, year level, and socio-economic status? Is there a significant relationship between the mathematics and competency levels of first year students of a University?
• Random variable


  A variable whose possible values are determined by chance
• Discrete random variable


  A quantitative variable whose value can only be attained through counting, with a finite or countably infinite number of possible values
• Continuous random variable


  A quantitative variable that can assume an infinitely many, uncountable number of real number values
• Classify the following random variables as discrete or continuous:

  1. The number of defective computers produced by a manufacturer

  2. The weight of newborns each year in a hospital

  3. The number of siblings in a family

  4. The amount of paint utilized in a building project

  5. The speed of a car

  6. The number of female athletes

  7. The average amount of electricity consumed per household

  8. The time needed to finish the test

  9. The number of voters favoring a candidate

  10. The amount of sugar in a cup of coffee
• Population


  The entire group of individuals or items that the researcher is interested in studying
• Sample


  A subset of the population that is selected for a research study
• The opinions of the Catholic Bishops' Conference of the Philippines (CBCP) regarding guidelines for the Liturgical Celebration in the "New Normal" condition
• Population


  • Catholic Bishops in the Philippines
• Sample


  • Bishops in Luzon
• Population


  • Viewers of the most popular TV noontime show in the Philippines
• A survey on the most popular TV noontime show in the Philippines
• Population


  • Public senior high school students in selected schools in Manila
• Sample


  • Public senior high school students in selected schools in Manila
• Population


  • Parents in Quezon Province
• Sample


  • Parents in Quezon Province
• Population


  • Students
• Sample


  • Students
• Probability or random sampling


  Involves selecting individuals or items from a population in such a way that each member of the population has an equal chance of being chosen
• Non-probability or non-random sampling


  Does not involve random selection, and the probability of selection is unknown