Week3

• Variables refer to a person, place, thing, or phenomenon that is being measured in some way
• Variables are characteristics of the individuals within the population that are being observed
• Variables are intended to be observed and measured at a given time and conditions due to their varying nature
• Independent Variable


  • Something that is changed by the researcher
  • What is naturally occurring groups to observe
  • What is manipulated
• Dependent Variable


  • Something that might be affected by the change in the independent variable
  • What is observed
  • What is measured
  • The data collected during the investigation
• Control Variable

  • Also called as constant variable
  • Identified and checked for consistency in experimental research setups
  • Should be the same throughout the samples to ensure no external factors may affect the dependent variable other than the independent variable itself
• Identifying IV and DV

  1. John: IV - sunlight, DV - size of leaves

  2. Madeleine: IV - height of a person, DV - how fast they run

  3. Akbar: IV - different brands of corn chips, DV - energy stored

  4. Jayden: IV - hair color, DV - common hair color for boy and girl classmates

  5. Sasha: IV - size of the ball, DV - ball's bounciness
• Qualitative variables


  • Yield categorical responses
  • Represent a class or category
  • Statistical analysis is limited
• Quantitative variables

  • Take on numerical values representing an amount or quantity
  • Most viable for statistical analysis
• Discrete variable


  • Quantitative variable with a finite or countable number of possible values
  • If you count to get the value, it is discrete
• Continuous variable


  • Quantitative variable with an infinite number of possible values that are not countable
  • If you use a measuring instrument to get the value, it is continuous
• A discrete variable is a quantitative variable that has either a finite number of possible values or a countable number of possible values. If you count to get the value of a quantitative variable, it is discrete
• A continuous variable is a quantitative variable that has an infinite number of possible values that are not countable. If you use a measuring instrument to get the value of a quantitative variable, it is continuous
• It is important to know which type of scale is represented by your data since different statistics are appropriate for different scales of measurement as this determines the amount of information contained in the data. The higher the level, the more information it can assume
• Types of scales of measurement

  • Nominal
  • Ordinal
  • Interval
  • Ratio
• Nominal Level


  Classifies persons or objects into two or more categories. Each person can only be in one category, and members of a given category have a common set of characteristics. Nonnumeric labels or numeric codes may be used
• Examples of Nominal Level


  • Method of payment (cash, check, debit card, credit card)
  • Type of school (public or private)
  • Eye Color (Blue, Green, Brown)
• Ordinal Level


  Ranks subjects in terms of the degree to which they possess a characteristic of interest. Puts subjects in order from highest to lowest, from most to least, but does not indicate how much higher or better a data is to others
• Examples of Ordinal Level

  • Food Preferences
  • Stages of Disease
  • Social Economic Class (First, Middle, Lower)
  • Severity of Pain
• Interval Level


  Classifies and orders measurements, specifies that distances between each interval on the scale are equivalent, and allows arithmetic operations like addition and subtraction. A value of zero does not mean the absence of the quantity
• Examples of Interval Level

  • Temperature on Fahrenheit/Celsius Thermometer
  • Credit Account
• Ratio Level


  Represents the highest, most precise level of measurement. Has properties of the interval level and ratios of values have meaning. A value of zero means the absence of the quantity. Allows arithmetic operations like multiplication and division
• Examples of Ratio Level

  • Temperature in Kelvin
  • Height and weight
  • Time
• Lord Kelvin: 'If you cannot measure it, you cannot improve it'