Laboratory and Field Experiments

Types of Scientific Studies Social scientific research can be divided into four categories: laboratory experiments field experiments field studies survey research. This breakdown stems from two sources: the distinction between experimental and nonexperimental research and between laboratory and field research.

Purposes of the Laboratory Experiment Test hypotheses derived from theory Study the precise interrelations of variables Control variance under research conditions that are uncontaminated by the operations of outside variables.

Strengths of Laboratory Experiments Situation Control: can isolate the research situation from the life and eliminate many extraneous influences. Multiple Tests and Attempts: can ordinarily use random assignment and can manipulate one or more independent variables. Precision: Precise laboratory results are achieved mainly by controlled manipulation and measurement in an environment from which possible “contaminating” conditions have been eliminated. Experiments can be repeated! Quantitative: by nature laboratory experiments collect quantitative data that is easily reproducible and can be agreed upon by many scientists.

Weakness of Laboratory Experiments Simplistic: Since laboratory situations are, after all, situations that are created for special purposes, it can be said that the effects of experimental manipulations are usually weak. Not Realistic: Although laboratory experiments have relatively high internal validity, they lack external validity.

Purposes of the Field Experiment Study living things in their natural environment. Understand the complex interactions of the natural world. Predict and minimize effects that threaten natural systems.

Strengths of Field Experiments Realistic: The variables are complex and subject to the laws of nature. Includes factors such as complex social and psychological influences, process, and changes in lifelike environments. Life is Complex: This type of experiment alone can attempt to understand the complex combinations of factors that contribute to relationships in nature.

Weaknesses of Field Experiments Unclear variables: In the field it is impossible to isolate and manipulate one variable while controlling all others. It is hard to isolate one variable to attribute the outcome to. Qualitative: Most data collected is qualitative and can be difficult to standardize. Often scientists must rely on unique scales to develop their own. Isolated Testing: Most experiments are so unique it is hard to randomize or repeat testing. This affects validity and reliability of the experiment. Observation effects: The simple act of observing organisms in the field often times alters their behavior. Scientists must carefully plan experiments to minimize their own effects on the data they are trying to collect.

Challenges we will look at How to estimate population sizes of living things. How to study animal behavior. How to investigate past conditions. How to identify species How environmental conditions can affect living things (if time)