Question 1

In what way does high within-groups variance obscure between-groups variance?
A) It leads to null results.
B) It leads to larger effect sizes.
C) It causes more overlap between experimental/comparison groups.
D) It limits the type of statistical analyses that can be conducted.

Accepted Answer

High within-groups variance causes more overlap between experimental/comparison groups, which makes it more difficult to detect differences in between-groups variance. This can lead to null results or smaller effect sizes. However, it does not limit the type of statistical analyses that can be conducted.

Question 2

Which of the following things can be done to reduce measurement error?
A) Using less precise measurements
B) Using more reliable measurements
C) Using a pretest/posttest design
D) Increasing unsystematic variance

Accepted Answer

Using more reliable measurements will help reduce measurement error, as they are more accurate and consistent than less reliable measurements. Using a pretest/posttest design and increasing unsystematic variance will not necessarily reduce measurement error. Using less precise measurements may actually increase measurement error.

Question 3

RESEARCH STUDY 11.2: Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white, odorless, tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again using the bomb calorimeter). The addition of a control group that does not use the drink additive would help Dr.Bloedorn address which of the following threats to internal validity?
A) History
B) Demand characteristics
C) Instrumentation
D) Placebo effects

Accepted Answer

Adding a control group that does not use the drink additive would help Dr. Bloedorn address the threat of history, which refers to any external event that may have influenced the outcome of the study (e.g. a new policy or event that affected the behavior of the participants). By having a control group, Dr. Bloedorn can see if any changes in calorie consumption during dinner are due to the additive or other external factors. The other options (B, C, D) are not applicable to the specific scenario described in the question.

Question 4

RESEARCH STUDY 11.2: Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white, odorless, tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again using the bomb calorimeter). The addition of a group that does not use the drink additive but adds a similar-looking substance that they think is the additive would help Dr.Bloedorn address which of the following threats to internal validity?
A) History
B) Observer bias
C) Instrumentation
D) Placebo effects

Accepted Answer

The addition of a group that adds a similar-looking substance that they think is the additive is a placebo group. This group helps to address the threat of the placebo effect, which is the tendency for people to respond differently when they believe they are receiving a treatment or intervention. By including a placebo group, Dr.Bloedorn can determine if any changes in calorie consumption are due to the additive or simply the participants' belief that they are consuming something that will help them eat fewer calories. The other options - history, observer bias, and instrumentation - are not relevant to this study.

Question 5

RESEARCH STUDY 11.2: Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white, odorless, tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again using the bomb calorimeter). Imagine that Dr.Bloedorn finds no difference between the calories consumed with the drink additive and without.This is known as:
A) observer bias.
B) a maturation effect.
C) a null effect.
D) the placebo effect.

Accepted Answer

This is known as a null effect, meaning that there is no significant difference between the two conditions. This suggests that the drink additive did not have an effect on reducing calorie consumption during dinner.

Question 6

A participant's score on a dependent variable is a combination of which of the following?
A) Measurement error and their true score
B) Systematic variance and error variance
C) Manipulation effect and observer bias
D) Their mean score and their standard deviation

Accepted Answer

A participant's score on a dependent variable is a combination of both measurement error and their true score. Measurement error can occur due to various factors such as lack of precision in measuring instruments, participant factors (such as fatigue, distraction, etc.), or experimenter factors (such as human error in recording data). True score refers to the participant's actual ability, attitude, or behavior being measured, which is what the researcher is interested in.

Question 7

A researcher's attempt to control sounds, smells, and even temperature in a testing environment is meant to reduce which of the following?
A) Between-group variance
B) Situation noise
C) Weak manipulations
D) Demand characteristics

Accepted Answer

Controlling sounds, smells, and temperature in a testing environment is meant to reduce situation noise, which refers to any extraneous factors in the environment that can influence participants' responses and thus increase within-group variance. This can compromise the validity of the study's results. By minimizing situation noise, researchers can increase the precision of their measurements and enhance the internal validity of their study. Between-group variance refers to differences between groups (e.g. control vs. experimental) that receive different treatments or manipulations. Weak manipulations and demand characteristics are not directly affected by environmental factors like sound, smell, or temperature.

Question 8

Which of the following is true of ceiling and floor effects?
A) They cannot be detected by manipulation checks.
B) They are only problematic in pretest/posttest designs.
C) They can be caused by poorly designed dependent variables.
D) They don't affect the results of a study.

Accepted Answer

Ceiling and floor effects can be caused by the dependent variable being poorly designed. For example, if the DV only goes up to a certain level, participants who score higher than that level will all be grouped together and not distinguished from each other, creating a ceiling effect. Similarly, if the DV starts at a low level and doesn't allow for lower scores, participants who score lower than that level will all be grouped together and not distinguished from each other, creating a floor effect.

Question 9

Which of the following is NOT a reason that a study might yield a null result?
A) A lack of between-group difference
B) Too much within-group variance
C) A "true" null result
D) Use of a within-subjects design

Accepted Answer

A within-subjects design typically increases statistical power and decreases variance, making it less likely to yield a null result. Therefore, using a within-subjects design would not be a reason for a study to yield a null result.

Question 10

Why is there a publication bias against null effects?
A) Null effects are not real.
B) Null effects are the result of badly designed studies.
C) People generally want to read about independent variables that matter.
D) Null results happen less often than significant results.

Accepted Answer

Publication bias against null effects often occurs because there is a general preference for reading about studies where the independent variables have a significant impact, making such findings seem more interesting or valuable.

Question 11

RESEARCH STUDY 11.2: Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white, odorless, tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again using the bomb calorimeter). Which of the following threats to internal validity will Dr.Bloedorn NOT be worried about?
A) Testing effect
B) Attrition
C) Demand characteristics
D) Placebo effects

Accepted Answer

Dr. Bloedorn will not be worried about attrition as it does not apply to this study. Attrition is a threat to internal validity when participants drop out of a study over time, potentially biasing the results. However, in this study, all 63 participants are included in both the pre-treatment and post-treatment measurements. The other threats to validity, including the testing effect, demand characteristics, and placebo effects, may all potentially affect the results of the study.

Question 12

Testing threats involve , whereas instrumentation threats involve .
A) researchers; participants
B) participants; measurements
C) independent variables; dependent variables
D) within-groups; between groups

Accepted Answer

Testing threats refer to the impact of repeated or practice measurements on participants, while instrumentation threats refer to changes in the measurement instruments themselves. Therefore, B is the correct choice for this question.

Question 13

Which of the following things can be done to reduce the effect of individual differences?
A) Using a matched-groups design
B) Decrease power
C) Collecting measurements from diverse groups of people
D) Using a between-groups design

Accepted Answer

The answer of Which of the following things can be...

Question 14

When a double-blind study is not possible, an acceptable alternative may be .
A) a matched groups design
B) a within-groups design
C) the use of a control group
D) a masked design

Accepted Answer

The answer of When a double-blind study is not possible,...

Question 15

Dr.Deveraux has conducted a study that has resulted in a null effect.Nonetheless, she suspects that there truly is a causal relationship between her independent and dependent variables.Which of the following is UNLIKELY to be to blame?
A) A weak manipulation
B) An insensitive measure
C) Too many participants
D) A reverse confound

Accepted Answer

The number of participants would not typically be a factor in producing a null effect. A larger sample size may actually increase the likelihood of discovering a statistically significant effect, but would not prevent a true causal relationship from being masked due to other factors such as a weak manipulation or insensitive measure. A reverse confound could also lead to a null effect despite the presence of a true causal relationship.

Question 16

A confound that keeps a researcher from finding a relationship between two variables is known as a(n) confound.
A) weak
B) insensitive
C) null
D) reverse

Accepted Answer

The answer of A confound that keeps a researcher from...

Question 17

Dr.Morimoto is curious as to whether exposing people to violent video games causes them to be more aggressive.He assigns half his participants to play a video game for 5 minutes and the other half to play for 7 minutes.He finds that there is no relationship between playing the game longer and being more aggressive.What might be to blame for this null effect?
A) A weak manipulation
B) An insensitive measure
C) A reverse confound
D) Ceiling effect

Accepted Answer

The null effect could be due to a weak manipulation where the level of violence in the game was not strong enough to elicit aggression in participants.

Question 18

Which of the following is a reason why a researcher might choose to conduct a double-blind placebo control group study?
A) To eliminate testing effects
B) To control for observer bias
C) To prevent attrition
D) To control for regression to the mean

Accepted Answer

A double-blind placebo control group study can control for observer bias, as neither the researcher nor the participants know who is receiving the treatment and who is receiving the placebo. This helps to eliminate any biases that may arise from knowing which group is receiving which treatment. The other options listed are not directly addressed by this type of study.

Question 19

Unsystematic variability in a study is also known as:
A) error variance.
B) null effect.
C) group inconsistency.
D) situational variability.

Accepted Answer

Unsystematic variability is due to the fluctuations that occur randomly in the study, and it is also known as error variance. This variability is typically caused by measurement errors, individual differences, and other random factors that can influence the outcome of the study. Therefore, the correct answer is (A) error variance.

Question 20

Dr.Sanderson is curious as to whether exposing people to violent video games causes them to be more aggressive.She assigns half her participants to play a violent video game for 5 minutes and the other half to play the same game for 25 minutes.Afterward, she has them play a board game and has a well-trained coder determine whether they are very aggressive in their playing style, barely aggressive, or not at all aggressive.She finds that a vast majority of her participants, regardless of group assignment, are rated as very aggressive.This outcome would be known as a(n):
A) weak manipulation.
B) ceiling effect.
C) floor effect.
D) outlier.

Accepted Answer

A ceiling effect occurs when a large proportion of participants score at the highest possible level or rating, which is what happened here with the vast majority of participants being rated as very aggressive regardless of the experimental manipulation.

Quiz 11: More on Experiments: Confounding and Obscuring Variables

In what way does high within-groups variance obscure between-groups variance?

Which of the following things can be done to reduce measurement error?

A participant's score on a dependent variable is a combination of which of the following?

A researcher's attempt to control sounds, smells, and even temperature in a testing environment is meant to reduce which of the following?

Which of the following is true of ceiling and floor effects?

Which of the following is NOT a reason that a study might yield a null result?

Why is there a publication bias against null effects?

Testing threats involve , whereas instrumentation threats involve .

Which of the following things can be done to reduce the effect of individual differences?

When a double-blind study is not possible, an acceptable alternative may be .

Dr.Deveraux has conducted a study that has resulted in a null effect.Nonetheless, she suspects that there truly is a causal relationship between her independent and dependent variables.Which of the following is UNLIKELY to be to blame?

A confound that keeps a researcher from finding a relationship between two variables is known as a(n) confound.

Which of the following is a reason why a researcher might choose to conduct a double-blind placebo control group study?

Unsystematic variability in a study is also known as: