How is a controlled experiment different from an observational study
Observational Study vs Experiment
so what's the difference between an
observational study and an experiment
it's a pretty significant difference
actually the difference between
observational study in an experiment is
that in an observational study the
researcher does not influence the
responses in any way they just stand
around and watch whereas in an
experiment the researcher deliberately
applies a treatment before observing any
of the responses so let me give you an
example here and an observational study
say I wanted to do a statistical study
on cars driving habits of people when
they come to a yellow light and I stand
off to the side and I'm just watching to
see what the cars are doing so the first
car comes by and it's a yellow light and
they stop and then once it turns green
they move on and I record what happens
and then the next car comes by and it
turns into a yellow light and this car
speeds up and goes through the light
because they're in such a hurry and then
I watch the next car and it's another
one and it turns yellow and wood speeds
through because it needs to get going as
well and the last car that I observe
turns into a yellow light and it
actually slows down and stops weights
and then once the light turns green it
moves on as well so in that case all I'm
doing is just watching I'm observing to
see what the cars and the or I should
say what the drivers are doing now how
can they turn this whole thing into an
experiment well instead of me just
standing around watching what if I stand
right next to the light
right on the corner and in my hand I
have a radar gun I'm going to write this
on there this is a radar gun right here
so I am standing here where the drivers
can see me and I have just applied a
treatment the treatment in this case
would be seeing the radar gun we want to
see how drivers react to a yellow light
when there is a radar gun a person
standing with the radar gun right next
to the yellow light that they're coming
up on so in this case the first car
comes by and they see the radar gun and
they stop and the next light comes by
light turns green and they go through
the next one comes by and this cars
coming uh-oh he sees the radar gun and
he stops as well and then the light
turns green and they move on the next
car is speeding up and then Oh
radar gun makes them stop as well and
then it turns green and they move on and
then there's another car here and
they're speeding up and it turns yellow
and they just go ahead and speed through
the light anyways so that's the main
difference between an observational
study in an experiment and the first
case I was just watching to see what
happens and what I was doing did not
influence what the drivers would do
whereas in the second example that would
be an experiment because I am applying a
treatment in this case seeing the radar
gun is the treatment and how once I see
how the drivers react not only am i
watching what they do but I'm applying
this treatment so
that I can see how the treatment affects
their driving habits
