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SOCI 301 Unit 7 Questions and Correct
Answers
effect size Ans: effect size is a measure of the difference between
populations
distinction between statistical significance and practical
significance Ans: a statistical test can sometimes return a
significant result, but the actual effect size is insignificant and of
no practical importance.
How to calculate effect size Ans: Cohen's d: Effect size=
(Population 1M - Population 2M)/Population SD
To calculate the standardized effect size, we divide the effect (that
is, the difference between the population means) by the population
standard deviation. If we don't have the SD of the population, we
can use the SD of one or the other of the groups in the study as an
estimate.
Cohen's effect size conventions Ans: Small d = ±.20
Medium d = ±.50
Large d = ±.80
A research article reports that eating a lot of sugary treats leads to
more cavities. The authors report the average number of cavities
per year for people who eat a lot of sugary treats is 2.2, while the
average number of cavities in those who do not eat a lot of sugar
is 1.4. Calculate the effect size. Is this a small, medium, or large
effect? Ans: The correct answer: .72 (Large). Note that Cohen's d
can be larger than one.
why and how do we standardize the effect size Ans:
Standardizing the effect size by dividing by the SD allows us to
© 2025 All rights reserved
SOCI 301 Unit 7 Questions and Correct
Answers
effect size Ans: effect size is a measure of the difference between
populations
distinction between statistical significance and practical
significance Ans: a statistical test can sometimes return a
significant result, but the actual effect size is insignificant and of
no practical importance.
How to calculate effect size Ans: Cohen's d: Effect size=
(Population 1M - Population 2M)/Population SD
To calculate the standardized effect size, we divide the effect (that
is, the difference between the population means) by the population
standard deviation. If we don't have the SD of the population, we
can use the SD of one or the other of the groups in the study as an
estimate.
Cohen's effect size conventions Ans: Small d = ±.20
Medium d = ±.50
Large d = ±.80
A research article reports that eating a lot of sugary treats leads to
more cavities. The authors report the average number of cavities
per year for people who eat a lot of sugary treats is 2.2, while the
average number of cavities in those who do not eat a lot of sugar
is 1.4. Calculate the effect size. Is this a small, medium, or large
effect? Ans: The correct answer: .72 (Large). Note that Cohen's d
can be larger than one.
why and how do we standardize the effect size Ans:
Standardizing the effect size by dividing by the SD allows us to
© 2025 All rights reserved
