NAPLEX Exam 1 Questions with Verified
Correct Answers
Important about P-value and CI
The use of P-value and confidence intervals is complementary. P-value allow a quick
decision about wether a result is statistically significant or not. Confidence intervals provide
information on statistical significance plus information about the direction and strength of
effect
What is the difference between Statistically significant and Clinically significant?
The measures of statistical significance is not the same as "clinical significance". Statistical
significance reflects the influence of chance on the outcome; clinical significance reflects the
clinical value of the outcome. Ex. if a blood pressure drug lowers SBP by 3 mmHg, it may be
statistically significant (with a p-value < 0.05) versus placebo, but clinically the drug will not
be used since other drugs lower BP to a greater degree.
Define Correlation?
Correlation describes the relationship between two or more variables which is then plotted on
a linear scale. Example how is disease progression and exercise correlated.
-> If positive correlation then 2 variables tend to increase or decrease together
-> If negative correlation then 2 variables are inversely related
-> If 0 correlation then the 2 variables have no relationship or correlation
Is there a positive correlation or negative correlation between exercise and diabetes
disease progression?
Negative correlation
What is type 1 error?
,The Greek letter, alpha (a) is the probability of type 1 error. The alpha value is chosen by the
researcher, before the study starts. A type 1 error occur when the null hypothesis is true, yet it
was rejected in error. When a researcher chooses the p-value of < 0.05 for statistical
significance, the researcher accepts the fact that this error will occur < 5% of the time. A type
1 erro is also known as false positive. To remember it easier " false positive study"
What is type 2 error?
The Greek letter, beta (B) is the probability of a type II error. Beta is generally set at 0.1 or
0.2, indicating a willingness to accept a type II error 10 or 20 times in 100 comparisons. A
type II error occur when the null hypothesis is false, yet it was accepted in error. A type2
error is also known as false negative. To remember it easier false negative study"
What is statistical power?
It is used to avoid type II error
SP = 1 - B
A higher statistical power means that we can be more certain that the null hypothesis was
correctly rejected
How to create a good statistical power?
The power of a study is determined by several factors including the sample size, the number
of events (MIs, strokes, deaths, etc), the effect size and the statistical significance criterion
used.
What is the difference between Dependent and Independent?
A dependent variable is the outcome of interest, which should change in response to some
intervention. An independent variable is the intervention, or what is being manipulated. For
example, aspirin is compared against placebo to see if it leads to a reduction in coronary
, events. The dependent variable (our outcome of interest ) is the number of coronary events
while the independent variable (the intervention) is aspirin
What is Discrete Date and what are the 2 types of discrete data?
Discrete Data - can have only a limited, or finite set of values (ie., not continuous) and can
assume only whoel numbers. The 2 types
1. Nominal: Consist of categories, where the order of the categories is arbitrary (e.g. martial
status, gender, ethnicity
2. Ordinal: consist of ranked categories, where the order of the ranking is important.
However, the difference between categories cannot be considered to be equal. Ex. Nominal:
pass/fail
Ordinal: A,B,C,D,F
What is Continuous data and what are the 2 types of Continuous data?
Continuous Data: Can take a infinite number of possible values (such as height, weight, A1C,
blood pressure) within a defined range. The 2 types
1. Interval: Interval data is used to measure continuous data that have legitimate mathematical
values. Ex. Celsius temperature scale
2. Ratio: Ratio data has equal intervals between values and a meaningful zero point; meaning
there is none of the variable (e.g. height, weight, time, length)
How to calculate the Relative Risk/Risk Ratio (RR)?
The relative risk (or risk ratio) is the probability of an unfavorable event occurring in the
treatment group versus he control group. First, the risk of developing the event must be
calculated for both the treatment group and the control group. Then the relative risk is
calculated by comparing the risk calculated for the treatment group (numerator) to the risk
calculated to the control group (denominator)
Correct Answers
Important about P-value and CI
The use of P-value and confidence intervals is complementary. P-value allow a quick
decision about wether a result is statistically significant or not. Confidence intervals provide
information on statistical significance plus information about the direction and strength of
effect
What is the difference between Statistically significant and Clinically significant?
The measures of statistical significance is not the same as "clinical significance". Statistical
significance reflects the influence of chance on the outcome; clinical significance reflects the
clinical value of the outcome. Ex. if a blood pressure drug lowers SBP by 3 mmHg, it may be
statistically significant (with a p-value < 0.05) versus placebo, but clinically the drug will not
be used since other drugs lower BP to a greater degree.
Define Correlation?
Correlation describes the relationship between two or more variables which is then plotted on
a linear scale. Example how is disease progression and exercise correlated.
-> If positive correlation then 2 variables tend to increase or decrease together
-> If negative correlation then 2 variables are inversely related
-> If 0 correlation then the 2 variables have no relationship or correlation
Is there a positive correlation or negative correlation between exercise and diabetes
disease progression?
Negative correlation
What is type 1 error?
,The Greek letter, alpha (a) is the probability of type 1 error. The alpha value is chosen by the
researcher, before the study starts. A type 1 error occur when the null hypothesis is true, yet it
was rejected in error. When a researcher chooses the p-value of < 0.05 for statistical
significance, the researcher accepts the fact that this error will occur < 5% of the time. A type
1 erro is also known as false positive. To remember it easier " false positive study"
What is type 2 error?
The Greek letter, beta (B) is the probability of a type II error. Beta is generally set at 0.1 or
0.2, indicating a willingness to accept a type II error 10 or 20 times in 100 comparisons. A
type II error occur when the null hypothesis is false, yet it was accepted in error. A type2
error is also known as false negative. To remember it easier false negative study"
What is statistical power?
It is used to avoid type II error
SP = 1 - B
A higher statistical power means that we can be more certain that the null hypothesis was
correctly rejected
How to create a good statistical power?
The power of a study is determined by several factors including the sample size, the number
of events (MIs, strokes, deaths, etc), the effect size and the statistical significance criterion
used.
What is the difference between Dependent and Independent?
A dependent variable is the outcome of interest, which should change in response to some
intervention. An independent variable is the intervention, or what is being manipulated. For
example, aspirin is compared against placebo to see if it leads to a reduction in coronary
, events. The dependent variable (our outcome of interest ) is the number of coronary events
while the independent variable (the intervention) is aspirin
What is Discrete Date and what are the 2 types of discrete data?
Discrete Data - can have only a limited, or finite set of values (ie., not continuous) and can
assume only whoel numbers. The 2 types
1. Nominal: Consist of categories, where the order of the categories is arbitrary (e.g. martial
status, gender, ethnicity
2. Ordinal: consist of ranked categories, where the order of the ranking is important.
However, the difference between categories cannot be considered to be equal. Ex. Nominal:
pass/fail
Ordinal: A,B,C,D,F
What is Continuous data and what are the 2 types of Continuous data?
Continuous Data: Can take a infinite number of possible values (such as height, weight, A1C,
blood pressure) within a defined range. The 2 types
1. Interval: Interval data is used to measure continuous data that have legitimate mathematical
values. Ex. Celsius temperature scale
2. Ratio: Ratio data has equal intervals between values and a meaningful zero point; meaning
there is none of the variable (e.g. height, weight, time, length)
How to calculate the Relative Risk/Risk Ratio (RR)?
The relative risk (or risk ratio) is the probability of an unfavorable event occurring in the
treatment group versus he control group. First, the risk of developing the event must be
calculated for both the treatment group and the control group. Then the relative risk is
calculated by comparing the risk calculated for the treatment group (numerator) to the risk
calculated to the control group (denominator)
