Question 1

Statistical power can be defined as:
A)the strength of the effect that you observe in your research
B)the ability of a study to reject a false null hypothesis
C)the value of the p-value that you get from your inferential statistical test
D)all of the above

Accepted Answer

Statistical power is the probability that a study will reject a false null hypothesis, meaning it can detect an effect if there is one to be detected.

Question 2

If you have a probability of 3 in 15 what is this expressed as a percentage?
A)3%
B)15%
C)20%
D)30%

Accepted Answer

To convert a probability into a percentage, you divide the numerator by the denominator and then multiply by 100. So, $ \frac{3}{15} \times 100 = 20\%$.

Question 3

Which of the following involves random sampling?
A)Snowball sampling
B)Volunteer sampling
C)Opportunity sampling
D)None of the above

Accepted Answer

None of the options listed (A: Snowball sampling, B: Volunteer sampling, C: Opportunity sampling) involve random sampling. Each of these methods involves non-random selection of participants.

Question 4

What type of distribution is represented in the following histogram? 
A)A negatively skewed distribution
B)A positively skewed distribution
C)A bimodal distribution
D)A normal distribution

Accepted Answer

The answer of What type of distribution is represented in...

Question 5

If you reject the null hypothesis when it is in fact true in the population, then what type of error have you made?
A)A Type I error
B)A Type II error
C)A calculation error
D)All of the above

Accepted Answer

The answer of If you reject the null hypothesis when...

Question 6

describe populations whereas describe samples:
A)People, researchers
B)Statistics, parameters
C)Parameters, statistics
D)Researchers, people

Accepted Answer

Parameters describe populations, while statistics describe samples. Parameters are summary measures that describe an entire population, and statistics are summary measures that describe a sample, which is a subset of the population.

Question 7

Which of these has a probability of 0.167?
A)Rolling an even number on a die
B)Rolling an odd number on a die
C)Rolling a number greater than 4 on a die
D)Rolling a 6 on a die

Accepted Answer

Rolling a 6 on a die has a probability of 1/6, which is equal to 0.167, since there is only one 6 on a standard six-sided die.

Question 8

Which of the following make assumptions about the distributions in populations?
A)Inferential tests
B)Parametric tests
C)Non-parametric tests
D)All of the above

Accepted Answer

Parametric tests assume that the data follows a certain distribution, typically a normal distribution. Non-parametric tests do not make such assumptions, and inferential tests is a broad category that includes both parametric and non-parametric tests.

Question 9

What happens to sampling error when you randomly select larger samples?
A)It increases
B)It disappears altogether
C)It decreases
D)It becomes negligible

Accepted Answer

Sampling error decreases as the sample size increases because a larger sample is more likely to closely represent the population, reducing the discrepancy between the sample and the population characteristics.

Question 10

If you have a score of 16 from a sample with a mean of 12 and a standard deviation of 2 then what would be the z-score?
A)-2
B)-1
C)1
D)2

Accepted Answer

The z-score is calculated by subtracting the mean from the score and then dividing by the standard deviation: $z = \frac{(score - mean)}{standard deviation} = \frac{(16 - 12)}{2} = \frac{4}{2} = 2$.

Question 11

Snowball sampling has which of the following characteristics?
A)Randomly selecting people from a population
B)Relying on people to volunteer to participate
C)Relying on referrals from people who have already taken part in a study
D)None of the above

Accepted Answer

Snowball sampling involves participants referring other participants from their network, making it reliant on referrals from those already part of the study.

Question 12

Which of the following is a one-tailed hypothesis?
A)There will be a difference between smokers and non-smokers in breathlessness
B)There will be a relationship between numbers of cigarettes smoked and degree of breathlessness
C)As the number of cigarettes smoked increases, then so will rating of breathlessness
D)None of the above

Accepted Answer

A one-tailed hypothesis predicts the direction of the effect, such as stating that one variable will increase or decrease as another variable does. Option C specifically predicts that as the number of cigarettes smoked increases, the rating of breathlessness will also increase, indicating a directional hypothesis.

Quiz 3: The Basis of Statistical Testing

Statistical power can be defined as:

If you have a probability of 3 in 15 what is this expressed as a percentage?

Which of the following involves random sampling?

What type of distribution is represented in the following histogram?

If you reject the null hypothesis when it is in fact true in the population, then what type of error have you made?

describe populations whereas describe samples:

Which of these has a probability of 0.167?

Which of the following make assumptions about the distributions in populations?

What happens to sampling error when you randomly select larger samples?

If you have a score of 16 from a sample with a mean of 12 and a standard deviation of 2 then what would be the z-score?

Snowball sampling has which of the following characteristics?

Which of the following is a one-tailed hypothesis?