7/25/2019 Components in Causal Studies

1/2

CRITICAL THINKINGCOMPONENTS OF CAUSAL STUDIES

Causal Hypothesis: Everything starts with a causal hypothesis. A causalhypothesis is a supposition or theory about how things interact, specifically,on whether one thing causes another. The purpose of causal studies is toconfirm or reject any given causal hypothesis. For example, a causalhypothesis we might want to see evidence for the idea that inhaling chaldust causes asthma.

Cause: A cause is something that is thought to bring about somethingelse. For example, we might thin that inhaling chal dust causes asthma.!iven this causal hypothesis the cause would be the inhaling of chal dust.

Causal fato!" Almost all the time any given effect is caused by aninteraction of many factors. As a result, we cannot say that any one thing,such as inhaling chal dust, is the actual cause of cancer in an individual."nstead we can usually only show that something, such as inhaling chaldust, is a causal factor in producing a certain effect in a group of people.

Effet: An effect of something is the result brought about by that thing orcause. For example, we might thin that asthma is an effect of inhalingchal dust.

Causal Stu#ies" #ausal studies are studies designed to test a causalhypothesis. For example, we might create a causal study to provideevidence for the hypothesis that inhaling chal causes asthma. #ausalstudies loo for causal factors in studies of groups or populations of people.

COMPONENTS OF A CAUSAL STUD$E%pe!i&e'tal G!oup: The experimental group is the group of individualsthat either$%& have been subjected to the supposed causal agent already,

$nonexperimental cause'to'effect studies&, or

$(& display the effect being studied $nonexperimental effect'to'causestudies&, or

$)& are subjected to the supposed cause being studied $controlled cause'to'effect studies&.

7/25/2019 Components in Causal Studies

2/2

Co't!ol G!oup: The control group is a group of individuals that have notbeen exposed to the supposed cause or do not display the supposedeffect. *hen selecting the control group it is important for the control groupto be as much lie the experimental group as possible, with the exceptionof either having been exposed to the cause or displaying the effect. Forexample, if we were going to use a controlled cause'to'effect study to testthe hypothesis that inhaling chal dust contributes to asthma, we wouldselect a group of people who are representative of the general population,and then we would divide the group into an experimental group and acontrol group. Then we would expose the experimental group to thesuspected causal agent.

F!e(ue'y: The fre+uency of either the experimental or control group is

the percentage of the group that displays the effect. For example, in astudy attempting to correlate chal intae with asthma, the fre+uency of theexperimental group would be the percentage of the experimental group thatshowed the effect $lets say -&. "n contrast, the fre+uency of the controlgroup would be the percentage of people in the control group that displaythe effect at the end of the study.

Diffe!e'e: The difference between the fre+uencies of the experimentalgroup and the control group is what is used to evaluate the causalhypothesis correlating the supposed causal factor and the effect. Thedifference is the difference between the percentages of the fre+uencies ofthe control and experimental group. For example, if - of theexperimental group develop asthma after having inhaled a certain amountof chal dust, and (- of the control group develop asthma even withoutthe chal dust, the difference would be )-.

Statistial Si)'ifia'e: To say that certain study results $i.e. certaindifference in fre+uencies& is statistically significant is to say that it would beunreasonable to attribute the difference to the results of chance. To assess

statistical significance you can use a table that correlates the difference infre+uencies with the si/e of the control group.