Question

It is recommended that a study has 200 participants. Only 80 participants signed up. If the study does continue with the 80 participants what should the researchers worry about? Alpha error, power error, type I error or type II error.

Answer #1

Correct option:

**Power Error**

Explanation:

Power = 1 - ,

where is the Type II Error, the probability of failing to reject the null hypothesis when the null hypothesis is not true.

So, if the Sample Size = n becomes smaller from 200 participants to 80 participants, the Standard Error becomes large. Thus. sampling distribution becomes wider. Thus, becomes large. Thus, Power becomes small.

7. Which study will require a larger sample size, one done with
80% power or 90% power when alpha (type I error) is set at 0.05 and
we use the same population and expected difference and variation
for both studies?

In a study about dieting and weight loss, N=80 subjects were
gathered to participate. All of the participants were approximately
20-25% overweight (from their ideal weight), with no habits of
exercising. The researchers randomly assigned these participants
into four different categories: participants in Category I (N=20)
ate the traditional low-caloric diet, participants in Category II
(N=20) ate the ketogenic diet, participants in Category III (N=20)
were told to eat whatever they want as if they were not on a diet...

The National Cancer Institute conducted a 2-year study to
determine whether cancer death rates for areas
near nuclear power plants are higher than for
areas without nuclear facilities. A spokesperson
for the Cancer Institute said, "From the data at hand, there was no
convincing evidence of any increased risk of death from any of the
cancers surveyed due to living near nuclear
facilities.” (1 points for each)
Let p denote the proportion of the population in areas
near nuclear...

The National Cancer Institute conducted a 2-year study to
determine whether cancer death rates for areas
near nuclear power plants are higher than for
areas without nuclear facilities. A spokesperson
for the Cancer Institute said, "From the data at hand, there was no
convincing evidence of any increased risk of death from any of the
cancers surveyed due to living near nuclear
facilities.” (1 points for each)
Let p denote the proportion of the population in areas
near nuclear...

1. When researchers conclude that their hypotheses are supported
based on samples, when in reality the hypotheses are not true of
the populations, the researchers have made __________________.
critical value errors
Type IV errors
Type II errors
2. Statisticians do not rely on the results of one study; thus,
_____________ is central to the connection between research and
understanding.
correlation
power
error variance
replication
3. Anna has conducted a study to test the hypothesis that fear
correlates to the number...

Statistical power analysis seeks to optimize the size of the
___________.
difference
sample
population
correlation
Statistical power is the likelihood that an effect will be
detected in the sample when one ____________.
is hypothesized to exist
has been found in previous research
really exists
exists in a previous sample of the same population
The probability of failing to detect an effect when one exists
is known as a _______.
Type I error
Type II error
Power
Standardized error
Which of...

Question 3
A study aims to determine the incidence of type 2 diabetes. A
cohort of 200 people age 65 years or older who were initially
disease –free participated in the study. One hundred and fifty
people were examined at the end of 3 years. Fifty other
participants from the initial cohort could not be examined,
including 11 people who had died. Does this loss of participants
represent a source of bias? Justify your answer. [4
points]
Question 4
A...

A team of researchers has developed a new drug to treat atopic
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drug procedures better results than a commonly prescribed older
drug. The side effects of the two drugs are equivalent. The new
drug would be more expensive to produce compared to the older drug.
To address their research question, they will randomly assign
patients to either the new or old drug. Each patient will be
examined by...

Sam decides he wants to know whether 45% of his customers own
only one cat.
a. Set up the null and alternative hypothesis (DO NOT TEST).
b. If Sam wants to minimize the probability of making a
type 2 error, should he set alpha equal to 0.05 or
0.01? Explain.
c. In terms of the problem, what does it mean if he makes a
type 1 error?
d. What would be the consequences of making such an error?

Imagine that my study has a power of 0.60 to find a correlation
of 0.30 or higher. What does this 0.60 mean in probability
terms?
In what situation should we care the most about power?

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