Types of Variables. It is very important when designing a research study that the researcher fully understands the variables in the study in order for the results to be valid and have meaning. A variable is something in the study that can be changed such as a characteristic or a value. The most common types of variables, especially when study cause and effect relationships, are the independent and dependent variables. The independent variable is the one that can be controlled or manipulated.
What's the maximum speed you can travel on a freeway with a 65 mph speed limit and be absolutely guaranteed not to get a speeding ticket? 65 mph. That's why it's called a speed limit. Any faster and you will be violating the statute which sets the limit. Now... is it likely you'll get stopped and cited at 66 mph?
Speed limits in the United States. Speed limits in the United States are set by each state or territory. Highway speed limits can range from an urban low of 35 mph (56 km/h) to a rural high of 85 mph (137 km/h). Speed limits are typically posted in increments of five miles per hour (8 km/h).