### Quiz 2 Bio-statistical Applications in Public Health – Bio-statistics

In this Biostatistics chapter, we discuss Quiz 2, Binomial and Standard Normal Probability Distributions and bio-statistical applications in public health.

HIV status (i.e. being HIV+ or HIV-) is a continuous variable.

True

**False – correct**

In some cases, the probability of contracting HIV is equal to 1.20.

True

**False – correct**

When discussing binomial probabilities, the word “success” is arbitrary and does not necessarily meaning something good is occurring.

**True – correct**

False

Which of the following is a requirement for a binomial probability distribution?

Homoscedasticity

Homogeneity of Variance

**There is a set # of trials. – correct**

Responses are dependent.

In the statistical notation for the binomial probability formula, which letter represents the probability of failure?

p

n

x

**q – correct**

In the statistical notation for the binomial probability formula, which letter represents the number of successes?

n

q

**x – correct**

p

In the statistical notation for the binomial probability formula, which letter represents the number of trials?

x

q

**n – correct**

p

In the statistical notation for the binomial probability formula, which letter represents the probability of success in a single trial?

n

q

**p – correct**

x

A health researcher at a hospital is asking patients with a history of smoking to enroll in a smoking cessation program. Throughout the day, she asks 45 patients to enroll in the program, 14 agree to sign up.

What is the number of trails for the research above?

1

14

**45 – correct**

59

A recent study reported that the most people want to eat healthier, but do not know how to cook a low-cost, healthy meal.

To help people change their eating habits, a local health care center decides to offer a free nutrition and cooking program. During the first program, 10 people attended.

One week after the program, each participant is contacted and asked if they have eaten healthier this week. Seven participants say “yes” and three participants say “no”.

In the following study, what does x equal?

10

3

**7 – correct**

1

What is the probability of obtaining a random score (X) less than or equal to 1.645?

P (X ≤ 1.645) ?

-0.90

**0.95 – correct**

0.90

-0.96

Along the x-axis of the standard normal distribution, you will find _____.

the area

**z-scores – correct**

y-scores

frequency

What is the probability of obtaining a random score (X) less than or equal to -1.96?

P(X ≤ -1.96) = ?

*Hint: Remember to use the negative z-score page!*

**0.0250** **– correct**

0.25

0.020

0.50

What is the probability of selecting a random score (X) that is greater than or equal to -1.96, but less than or equal to 1.96?

P( -1.96 ≤ X ≤ 1.96) = ?

0.90

-0.95

**0.95** **– correct**

-0.25

What is the probability of randomly selecting a score (X) greater than or equal to 2.00?

P( 2.00 ≤ X) ?

1.9727

0.9772

**0.0228** **– correct**

0.2828

The standard deviation of a standard normal distribution is always equal to 1.

**True – correct**

False

All normal distributions have a mean of zero.

True

**False – correct**

ExplanationAll STANDARD normal distributions have a mean of 0.Normal distributions have different means and standard deviations, depending upon the where the data is coming from. However, normal distributions take on the same bell-shape as the standard normal distribution AND we can use the z-score formula to convert or standardized the distribution.

The entire area under the curve of the standard normal distribution is equal to 1.

**True – correct**

False

The area in a probability distribution is used to calculate the probability of different events or scores.

**True – correct**

False

Probability distributions are used in statistical analyses.

**True – correct**

False