18. October, 2016Uncategorized

1. Researchers have developed a new filament for 60 watt light bulbs. A sample of the new light bulbs is plugged into a usage monitor at the laboratory, and the number of hours before burning out is recorded for each bulb. A sample of the old light bulbs is tested also.

1.Independent Variable

2.Dependent Variable

3.Testable experimental question

4.formal hypothesis

5.3 variables that must be constant

6.control group

7.experimental group

Answer key:

Independent Variable – the type of filament in the bulb (new verses original)

Dependent Variable – number of hours before burning out

Testable question – Will the light bulbs with a new filament take longer to burn out than a light bulb with the original filament?

Formal Hypothesis – If the number of hours until burning out is related to the type of filament in the bulb, then bulbs with the new filament will take longer to burn out than bulbs with the original filament.

Constants – wattage of the bulbs, same usage monitor, same amount of electricity flowing to each bulb, same room conditions; same outlet

Control group – light bulbs with the original filaments

Experimental group – light bulbs with the new filament

2.

A biopsychologist is studying the effects of anabolic steroids on the aggressive behavior of female rats. 24 female rats receive daily injections of a placebo (fake drug), while 24 others receive daily injections of the steroid. Round-the-clock videotapes of the communal cages of all rats allow all aggressive encounters to be counted and timed.

1.Independent Variable:

2.Dependent Variable:

3.Experimental Group:

4.Control Group:

Answer key:

1. Independent Variable:  injections of the steroid or placebo
2. Dependent Variable: number of aggressive encounters and how long the aggressive encounters lasted
3. Experimental Group: female rats receiving the steroid
4. Control Group: female rats receiving the placebo