Scientific Method Review

1. Scientific Method Review • Lets review Definitions • Then we’ll practice by identifying variables in example experiments • Afterwards you’ll be prepared to design your own experiment

2. Control Group- group which does not receive treatment; “business as usual”; baseline used for comparison • Experimental Group- group which receives the treatment; tests experimental variable • Independent Variable- difference between the control group and the experimental group (changed before the experiment) • Dependent Variable- change which occurs during experiment due to the independent variable • Bias- personal opinions (preconceived ideas) which alter experimental data • Placebo- a fake used to trick subjects into thinking they are receiving the treatment • Hypothesis- educated guess about what will happen in experiment. In IF/THEN form

3. #1 Todd raced dirt bikes and had been losing regularly. He wondered if his brand of bike was the reason for his losses and what the fastest dirt bike brand was. He went to a shop that allowed their bikes to be test driven outback of their store. He rode his bike outback first. Then he rode a Kawasaki, a KTM, a Suzuki, and a Honda the same distance and timed the ride. What is the: • Control Group: _______________________________________ • Experimental Group: __________________________________ • Independent Variable: _________________________________   • Dependent Variable: __________________________________

4. #1 Todd raced dirt bikes and had been losing regularly. He wondered if his brand of bike was the reason for his losses and what the fastest dirt bike brand was. He went to a shop that allowed their bikes to be test driven outback of their store. He rode his bike outback first. Then he rode a Kawasaki, a KTM, a Suzuki, and a Honda the same distance and timed the ride. What is the: • Control Group: Todd timing his old bike outback • Experimental Group: Todd timing the new bikes on the same course • Independent Variable: brand of bike • Dependent Variable: speed (time it took to complete the race)

5. #2 Demi enjoyed watching TV afterschool. She just became a 9th grader and was receiving more homework than she was used to. Her teacher told her she’d have to cut down on her TV habits or her grade would suffer. Demi wondered if watching TV really affected a student’s grade. She had a group of her TV viewing friends maintain their viewing schedule and another group stop watching completely and checked their grades after two weeks. What is the: • Control Group: _______________________________________ • Experimental Group: __________________________________ • Independent Variable: _________________________________   • Dependent Variable: __________________________________

6. #2 Demi enjoyed watching TV afterschool. She just became a 9th grader and was receiving more homework than she was used to. Her teacher told her she’d have to cut down on her TV habits or her grade would suffer. Demi wondered if watching TV really affected a student’s grade. She had a group of her TV viewing friends maintain their viewing schedule and another group stop watching completely and checked their grades after two weeks. What is the: • Control Group: group which continued their TV viewing schedule • Experimental Group: group which stopped watching TV • Independent Variable: amount of TV watched • Dependent Variable: students grades

7. #3 Pat worked for a landscaping company that manicured lawns in the neighborhood. He noticed one hot summer that a lot of the lawns that received services twice a week were actually browner than lawns that were only mowed once a week. He asked himself if the length of the grass (number of times cut) affected the health of the lawn. He began keeping a logbook describing the appearance of lawns that were mowed twice a week and those he tended to once a week. What is the: • Control Group: _______________________________________ • Experimental Group: __________________________________ • Independent Variable: _________________________________   • Dependent Variable: __________________________________

8. #3 Pat worked for a landscaping company that manicured lawns in the neighborhood. He noticed one hot summer that a lot of the lawns that received services twice a week were actually browner than lawns that were only mowed once a week. He asked himself if the length of the grass (number of times cut) affected the health of the lawn. He began keeping a logbook describing the appearance of lawns that were mowed twice a week and those he tended to once a week. What is the: • Control Group: Lawns he cut once a week • Experimental Group: Lawns he observed being cut twice a week • Independent Variable: length of grass (number of times cut)   • Dependent Variable: health of the grass (color)

9. #4 Pamela had recently entered her homemade brownies into a baking contest and lost. On her scoring entry from the judges there were comments about the brownies texture saying her brownies were too hard and reminded the judges of bricks. Pamela wondered what could have happened. Her brownies typically receive great reviews. She asked herself if the amount of time the brownies bake in the oven affects the texture of the brownies. She placed a batch of brownies in the oven for the same amount of time as her losing brownies and then put a second batch in the oven at the same temperature but removed them 5 minutes sooner than the other batch. What is the: • Control Group: _______________________________________ • Experimental Group: __________________________________ • Independent Variable: _________________________________   • Dependent Variable: __________________________________

10. #4 Pamela had recently entered her homemade brownies into a baking contest and lost. On her scoring entry from the judges there were comments about the brownies texture saying her brownies were too hard and reminded the judges of bricks. Pamela wondered what could have happened. Her brownies typically receive great reviews. She asked herself if the amount of time the brownies bake in the oven affects the texture of the brownies. She placed a batch of brownies in the oven for the same amount of time as her losing brownies and then put a second batch in the oven at the same temperature but removed them 5 minutes sooner than the other batch. What is the: • Control Group: batch of brownies backed the usual amount of time • Experimental Group: batch of brownies taken out of the oven 5 min sooner • Independent Variable: amount of time in the oven • Dependent Variable: texture of the brownie

11. #5 • A developmental psychologist is testing the hypothesis that children in first grade know more words in the English language than children in Kindergarten. To test this, she sits in on two classes (one first grade, the other Kindergarten) and counts the average number of words children in each class speak. She then compares the counts. • Independent variable: ________________________________ • Dependent variable: ________________________________

12. #5 • A developmental psychologist is testing the hypothesis that children in first grade know more words in the English language than children in Kindergarten. To test this, she sits in on two classes (one first grade, the other Kindergarten) and counts the average number of words children in each class speak. She then compares the counts. • Independent variable: age/grade of students • Dependent variable: number of words spoken

13. #6 • A pharmacologist is testing whether a new anti-anxiety medication, Moodcor, will cause people to gain weight. To test this, she gives 100 people Moodcor for one month and 100 people a placebo drug. At the end of the month, she monitors any weight gain. • Independent variable: ________________________________ • Dependent variable: ________________________________

14. #6 • A pharmacologist is testing whether a new anti-anxiety medication, Moodcor, will cause people to gain weight. To test this, she gives 100 people Moodcor for one month and 100 people a placebo drug. At the end of the month, she monitors any weight gain. • Independent variable: type of drug individuals receive (placebo or Moodcor) • Dependent variable: weight gain

15. #7 • A personality psychologist believes that people who are more aggressive are more likely to purchase sports coupes than people who are less aggressive. To test this, he visits local car dealerships and asks car shoppers to complete an aggression survey. Then, he observes what types of cars they purchase (sports coupe, sedan, SUV, or pickup). • Independent variable: ________________________________ • Dependent variable: ________________________________

16. #7 • A personality psychologist believes that people who are more aggressive are more likely to purchase sports coupes than people who are less aggressive. To test this, he visits local car dealerships and asks car shoppers to complete an aggression survey. Then, he observes what types of cars they purchase (sports coupe, sedan, SUV, or pickup). • Independent variable: aggression (based on results from aggression survey) • Dependent variable: types of cars purchased

17. #8 • A clinical psychologist hypothesizes that listening to an inspirational tape will lead one to be in a better mood. To test this, she has 50 people listen to an hour-long inspirational tape. Another 50 listen to white noise for an hour. She then has them rate their mood on a 10-point scale. • Independent variable: ________________________________ • Dependent variable: ________________________________

18. #8 • A clinical psychologist hypothesizes that listening to an inspirational tape will lead one to be in a better mood. To test this, she has 50 people listen to an hour-long inspirational tape. Another 50 listen to white noise for an hour. She then has them rate their mood on a 10-point scale. • Independent variable: type of noise they listen to (inspirational tape vs white noise) • Dependent variable: mood

19. #9 • A clinical psychologist is testing his theory that people who experienced a brain injury are developmentally delayed to the age at which they experienced the injury (for instance, if one has a brain injury at the age of 10, that person will always act like they are 10). To test this, he conducts developmental interviews with two people who experienced a brain injury at two different ages (one was 3 and one was 20). • Independent variable: ________________________________ • Dependent variable: ________________________________

20. #9 • A clinical psychologist is testing his theory that people who experienced a brain injury are developmentally delayed to the age at which they experienced the injury (for instance, if one has a brain injury at the age of 10, that person will always act like they are 10). To test this, he conducts developmental interviews with two people who experienced a brain injury at two different ages (one was 3 and one was 20). • Independent variable: age of initial brain injury • Dependent variable: the age the person acts

21. Design It • 10. Do lightening bugs get brighter in warmer temperatures? • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:

22. Design It • 10. Do lightening bugs get brighter in warmer temperatures? Control Group: lightening bug at room temperature (65*F) Experimental Group: lightening bug at slightly warmer temperature (75*F) Independent Variable: temperature Dependent Variable: brightness of bug

23. Design It • 11. Does popcorn pop quicker at lower pressures? • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:

24. Design It • 11. Does popcorn pop quicker at lower pressures? Control Group: popcorn popping at normal atmospheric pressure Experimental Group: popcorn popping at lower atmospheric pressure (on a mountain maybe) Independent Variable: amount of pressure Dependent Variable: time it takes to pop

25. Design It • 12. What color of light causes the highest rate of photosynthesis in bamboo? • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:

26. Design It • 12. What color of light causes the highest rate of photosynthesis in bamboo? Control Group: Bamboo growing in white light (normal sunlight) Experimental Group: bamboo plants growing under different colored lights: red, blue, green, etc. Independent Variable: color of light Dependent Variable: rate of photosynthesis (growth rate or amount of oxygen given off)

27. Design It • 13. What amount of food per gram of goldfish will produce the optimal growth rate? • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:

28. Design It • 13. What amount of food per gram of goldfish will produce the optimal growth rate? Control Group: fish receiving the normal recommended amount of food Experimental Group: one group receiving 1 gram more and one group receiving one gram less Independent Variable: amount of food Dependent Variable: growth rate of fish

29. Design It • 14. Does groGreen (a fertilizer) cause a higher growth rate in grass? • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:

30. Design It • 14. Does groGreen (a fertilizer) cause a higher growth rate in grass? Control Group: grass growing without groGreen Experimental Group: grass growing with groGreen Independent Variable: whether or not it is getting groGreen Dependent Variable: growth rate

31. YOUR TURN 15. Design your own! Describe what you are testing • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable: