Independent & Dependent Variables Mrs. Nell 8th Physical Science Chapter 1 Practice

A-maze-ing Mr. Beaker wants to examine whether a new drug increases the maze running performance of older rats. Just like aging humans, older rats show signs of poorer memory for new things. Dr. Ooze teaches two groups of older rats to find a piece of tasty rat chow in the maze. One group of rats is given the new drug while they are learning the maze. The second group is not given the drug. One week after having learned the maze he retests the rats and records how long it takes them to find the rat chow. Control group: Second group What is the independent variable? Presence or absence of the new drug What is the dependent variable? Length of time it took the rats to remember where the rat chow was after one week.

Zzzzz…. A researcher wanted to study the effects of sleep deprivation on physical coordination. The researcher selected 25 year-old male college students and deprived some of the subjects to either 24, 36, or 45 hours of sleep. Control Group Independent Variable Dependent Variable Control: not deprived of sleep Indep: Time of Sleep deprivation Dep: phys. Coordination

Off Balance A researcher conducts an experiment to assess the effects of alcohol on people’s sense of balance. He divides his subjects into three groups: in one group the participants drink soda. He then watches as each participant tries to walk on a straight line from one corner of the room to the next and notes how many times they stumble outside the line. Control: soda group Indep: alcohol Dep: sense of balance (as measured by # of stumbles) Control Group Independent Variable Dependent Variable

Hypnotize Me An investigator had 60 subjects watch a videotaped re-enactment of a bank robbery. Half of the subjects were asked by a police investigator to recall the event, while the remaining subjects were interviewed by a police investigator while they were hypnotized. Control: Those asked to recall the event without being hypnotized Indep: whether subjects were hypnotized Dep: How much subjects recalled Control Independent Variable Dependent Variable

If You Say So… A researcher wanted to know whether the number of people present would influence subjects’ judgments on a simple perceptual task. In each case, the other members of the group gave an incorrect answer. The researcher then noted whether the subject conformed to the group decision. Indep: # of people in group Dep: whether subjects conformed with the group Independent Variable Dependent Variable

Back to Bach A researcher is curious to find out what effect classical music has on people’s level of relaxation (as measured by heart rate). He suspects that listening to classical music will make people feel more calm and relaxed. He lets one group listen to classical music for one hour. He lets another group sit in a quiet room for one hour (i.e.- they hear no music). After one hour, he monitors the heart rate of each participant to measure their level of relaxation. Control: sitting in quiet room Indep: Classical Music exposure Dep: Level of relaxation, as measured by heart rate Control Group Independent Variable Dependent Variable

Green Slime Homer notices his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of “treatment” there is no change in the appearance of the green slime on either side of the shower. Control: side he sprayed with water Ind. Variable: coconut juice Dep. Variable: appearance of green slime Conclusion: coconut juice did not reduce slime in shower Control Group Independent Variable Dependent Variable What should Homer’s conclusion be?

Mighty Mice Bart believes that mice exposed to microwaves will become extra strong. He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of 10 of the non-microwaved mice were able to do the same. Control: mice not exposed Conclusion: did not cause mouse to become stronger than non-microwaved mice Indep: whether microwaved Improve by: testing more (doing more trials) Dep: strength of mice Control Group Independent Variable Dependent Variable What should Bart’s conclusion be? How could Bart’s experiment be improved?

Juicy Juice Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they’re supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks. Control: Group B Indep: Special Juice Dep: Productivity of workers Conclusion: special juice did not increase workers productivity Improve By: Control Group Independent Variable Dependent Variable What should Smithers’ conclusion be?

Krusty the Clown Krusty was told that a certain itching powder was the newest best thing on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes. Control: Group A Indep. Variable: Exper. Itching Powder Dep. Variable: Itchiness time Data support? Time was reduced by 1/3 so claim was not supported Control Group Independent Variable Dependent Variable Does the data support the ad’s claims about its product?