- Hi, my name is Sara Safari,
and I'll be walking us through a MCAT Psychology Passage,
and I'll just be going over the tips and strategies
that I used when I took the MCAT,
specifically for a psychology passage,
and we'll be going over it slower
than you would normally wanna go over an MCAT passage,
just to give you guys the full picture,
and so I can talk it through.
So let's keep that in mind and let's get to it.
(electronic swoosh)
(typewriter clacking)
Okay, so before I go into reading the passage,
I just wanna go over my strategy for when I read.
So I don't typically like to underline lots of things,
because I find that when I go to the questions,
the passage becomes cluttered, and I can't find anything,
and if I am gonna underline something,
I'll only underline the first portion of it.
But for the things that I do underline,
it would be related to anything
talking about a study protocol,
like sample size, control groups, things like this,
or something related to an abbreviation.
The first time it's abbreviated,
and then every time it shows up in a passage.
So let's get started.
Researchers have discovered that childhood exposure
to secondhand smoke can have detrimental effects
on a child's health and development.
Studies have shown that secondhand smoke can, one,
increase adulthood incidence of asthma,
two, decrease dopamine levels during adolescence,
three, affect cognitive processes like decision-making,
and four, increase adulthood incidence of cancer.
To study the effect of secondhand smoke during childhood
on adult health outcomes,
because this is the whole point of this study,
I'm going to underline it.
Researchers conducted a longitudinal study,
tracking 938 individuals
who lived in homes from ages zero through 10
with guardians who smoked at least
one pack a day of cigarettes.
As a control,
researchers also recruited 912 individuals
who lived in homes from ages zero to 10
with guardians who did not smoke any cigarettes.
Beginning at the age of 15, through the age of 60,
the researchers sent a survey to the study participants
to assess any physical or mental health conditions
that the participants had,
such as asthma, hypertension, diabetes, schizophrenia,
depression, anger issues, or cancer.
In the group that experienced secondhand smoke,
so the experimental group,
researchers found a higher incidence of all seven
physical and mental health conditions
that were outlined right here.
The greatest difference between the two groups was found
in the incidence of asthma.
So I'm gonna go back and circle it, just for emphasis.
54% of the individuals in the group
that experienced secondhand smoke
developed some form of asthma by age 60,
compared to 23% of the control group individuals.
Researchers also found that individuals
in the secondhand smoke condition
developed schizophrenia by the age of 60
at a higher percentage than control group individuals.
So that's schizophrenia, as well.
Let me zoom in a little bit for you guys to see,
I'm also gonna underline schizophrenia more, as well.
So in a follow up investigation,
researchers decided to broaden the scope of the study
to analyze socioeconomic factors.
Using average household income,
and neighborhood public school funding
as a proxy for socioeconomic status,
researchers found that low socioeconomic status individuals
had poorer health outcomes
irrespective of secondhand smoke during childhood.
So not depending on that secondhand smoke exposure.
So let's go into the questions.
A researcher points out ...
Actually before I read the question,
I typically will like to think of the answer to a question
before I look at the answer choices,
so I'm not influenced by them.
So let's go into the questions.
A researcher points out
that there's a difference in the size
of the secondhand smoke group and the control group,
which would invalidate the results of the study.
The concern is blank.
So first I want to go back to my passage,
and see what were the sizes of the secondhand smoke group
and the control group,
before I read any of the answer choices to be swayed.
So here I underlined the control group,
I'm sorry, no, the experimental group has 938 participants
and the control group has 912.
So here we go.
It was 938 here, and then the control was 912.
So the difference is 20 or so individuals
but this is a huge sample size,
so that many individuals is not really gonna make
a huge difference in terms of study sample size,
if let's say, for example,
the experimental group had 50 people in it,
and then the control group had 20 people in it,
then that's something more concerning,
so I don't think that there is a concern here,
so now let's look at the answer choices.
Valid, because the sample sizes must be equal
in order to achieve statistical significance.
That is not true.
So we're emitting it as an answer choice,
because sample sizes do not have to be exactly equal,
B, valid, because these unequal sample sizes
will produce bias.
Once again, this is basically saying
the same thing as A,
unequal sample sizes, it depends on how unequal they are,
if they will produce a bias,
you don't really have a calculator to see statistically
if what exactly the cutoff point is,
but this is a small enough difference
that you can use your own reasoning
to see that this is okay, so B is incorrect.
So now we're going to the invalid options,
we know it's one of these two, so we need to make sure
that the reason it's correct,
I mean, the reason that it's invalid
is the correct reasoning.
Invalid because a difference of 26 individuals
for two large sample sizes will not be significant.
This is pretty much the explanation I gave to you guys
when I read the answer choice,
so this is looking very like a good answer.
So let's look at the last one just for completeness,
invalid because statistical significance
is not based on sample size.
That's incorrect, because statistical significance
is based on sample size, so that's wrong, and C is correct.
Moving on to question two.
Which of the following most likely explains
the increased incidence of schizophrenia
in the secondhand smoke group?
So going to the passage,
I did underline schizophrenia here,
and this requires some knowledge about schizophrenia,
and it is related to dopamine levels,
and also if that is not knowledge that you have,
also right here in the passage,
we see that secondhand smoke has shown
to decrease dopamine levels.
Dopamine is the only neurotransmitter
that is mentioned in the entire passage,
and based off a knowledge of schizophrenia,
we know that it has to be the dopamine hypothesis,
and then just looking at the other answer choices,
serotonin is involved in depression,
acetylcholine is not involved in schizophrenia,
mostly it's in Alzheimer's,
and also acetylcholine and epinephrine hypotheses
are not commonly used,
it's mainly dopamine versus serotonin,
and in the case of schizophrenia,
dopamine is the correct answer.
Last question, in a new study, researchers discovered
that individuals with low socioeconomic status
experience worse health outcomes
than individuals with high socioeconomic status.
This result is best explained by which of the following?
So I can already tell
that this question requires knowledge of terms,
so let's see, gender inequality.
While we're talking about socioeconomic status,
we're not talking about gender here,
so this does not make sense.
Food deserts, option B.
I mean, this could be a contributing factor,
but I don't see it being the best answer choice.
Socioeconomic gradient of health,
this is the best answer choice here,
and epidemiology is the study of disease trends
in a population, which does not make sense here.
So the answer is the socioeconomic gradient of health.
This is the most correct answer.
And if you're just concerned about food deserts,
there are more food deserts in low socioeconomic areas,
but this is not the most correct answer.
Socioeconomic gradient of health
would best explain why individuals
with low socioeconomic status experience
worse health outcomes.
Okay?
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