VARIABLES Variable Defined: It is a property or quantity that can take on different values. Example: Effect of Light and Temperature on the Growth of Plants Kinds of Variables Independent Variable Dependent Variable Independent Variable It is the variable that is varied or manipulated by the researcher. An independent variable is the presumed cause Dependent Variable It is the response that is measured. A dependent variable is the presumed effect. Example 1 You are interested in “How stress affects mental state of human beings?” Independent variable - stress Dependent variable - mental state of human beings Example 2 Promotion affects employees’ motivation Independent variable promotion Dependent variable employees’ motivation Example 3 “Predictors of Students’ Performance in Chemistry Laboratory of Selected Private Schools” Independent variable - Chemistry Laboratory Activities Dependent variable - Students’ Performance A group of high school students were given a short course in speed-reading. The teacher was curious if a monetary incentive would influence performance on a reading test taken at the end of the course. Half the students were offered P50 for obtaining a certain level of performance on the test, the other half were not offered money. Does heating a cup of water allow it to dissolve more sugar? Does fertilizer make a plant grow bigger? Does an electric motor turn faster if you increase the voltage? How fast does a candle burn? Is a classroom noisier when the teacher leaves the room? How much water flows through a faucet at different openings? Extraneous Variables Extraneous Variables are undesirable variables that influence the relationship between the variables that an experimenter is examining. These are variables that influence the outcome of an experiment, though they are not the variables that are actually of interest. Example An educational psychologist has developed a new learning strategy and is interested in examining the effectiveness of this strategy. The experimenter randomly assigns students into two groups. All of the students study text materials on a biology topic for thirty minutes. One group uses the new strategy and the other uses a strategy of their choice. Then all students complete a test over the materials. Extraneous variable - pre-knowledge of the biology topic Does fertilizer make a plant grow bigger? Continuous Variables Are those that take fractional values Discrete Variables Are those that assume fixed or exact amounts Which of these are continuous? Which of these are discrete? • The number of Toyota • The length of travel cars sold by a car dealer time from in one year Tuguegarao to • The number of students Manila protesting the tuition • The depth of drilling increase last semester to find oil reserves • The number of teacher applicants for the T3 • The amount of soda position in a 20-ounce bottle Continuous or Discrete 1. Number of students engaged in sports 2. Memory capacity of a computer 3. Body temperature 4. Ages of fourth year students 5. Number of teachers in Pamplona Institute 6. Grade in Mathematics 7. Number of books in the shelf 8. Time consumed in taking a math exam 9. Distance traveled by a car 10.Dale’s height Experimental Variables Are those which are subjected to a certain treatment (with treatment) Control Variables Are those which are exposed to the absence of the treatment (without treatment) NOTE: • The same conditions hold for the two groups • The response to the treatment they received are compared to evaluate the effect of the IV A group of high school students were given a short course in speed-reading. The teacher was curious if a monetary incentive would influence performance on a reading test taken at the end of the course. Half the students were offered P50 for obtaining a certain level of performance on the test, the other half were not offered money. A farmer put organic fertilizer to the first row of his squash plants, but did not place any on the second row. • In the study of corn husk as antihypertensive alternative, students who conducted the experiment injected the solution to 10 mice. On the other hand, another 10 mice were left without any corn husk treatment. Enhancing Students’ Performance in Graphing Functions through Flipped Teaching Method Quantitative Variables Take on values that correspond to the points on a real line scale Qualitative Variables Take on values that are names or labels A deck of cards contains both quantitative and qualitative variables. • What are variables? • What are variables? the the qualitative quantitative • The quantitative variables are the number on the card • The qualitative variables are the suits (spade, clubs, heart, diamond) Qualitative or Quantitative 1. Gender 2. Age 3. Number of Family Members 4. General Weighted Average in High School 5. Type of School Levels of Measurement • The nominal level of measurement is characterized by data that consist of names, labels, or categories only. • The ordinal level of measurement involves data that may be arranged in some order but differences between data values either cannot be determined or are meaningless. Levels of Measurement • The interval level of measurement is like the ordinal level, but meaningful amounts of differences can be determined. It has no inherent (natural) zero starting point. • The ratio level of measurement is the interval level modified to include the inherent zero starting point. Identify the level of measurement for each of the following data. 1. Blood type of a patient admitted to a hospital 2. Intelligence Quotient of a student 3. Tax identification number (TIN) of an employee 4. A student’s academic rank in high school 5. Average daily sales of a bakeshop 6. TV network 7. Most popular movie actor 8. Birth order in the family 9. Body temperature 10. Memory capacity of a computer