Question 1

Multiple Groups Santana designed an experiment with four treatment conditions.If she has 20 subjects and decides to assign an equal number of subjects to each condition using block randomization, how many treatment blocks can she complete?

Accepted Answer

With 20 subjects and 4 treatment conditions, Santana can assign 5 subjects to each condition, resulting in 5 treatment blocks.

Question 2

Two Matched Groups Which matching procedure sometimes creates groups with unacceptably large differences on the matching variable?

Accepted Answer

The answer of Two Matched Groups Which matching procedure sometimes...

Question 3

Two Independent Groups The most serious dilemma posed by waiting-list control conditions in medical and psychotherapy research is that

Accepted Answer

Waiting-list controls deny treatment to patients who need it, which raises ethical concerns and can harm the physical or mental health of participants.

Question 4

Two Matched Groups Researchers will always create treatment groups of equal size if they use ____ to randomly assign subjects to treatment conditions.

Accepted Answer

Block randomization ensures equal size treatment groups by dividing the total sample size into blocks and ensuring equal allocation of subjects to each treatment group within each block. This method reduces the chance of unequal group sizes occurring by chance, making it a reliable technique for creating matched groups. Random number tables are a form of simple randomization that do not guarantee equal group sizes, while subject-by-subject counterbalancing and across-subjects counterbalancing are techniques used within a single group rather than for creating matched groups.

Question 5

Two Matched Groups Which matching procedure usually discards the most data?

Accepted Answer

Precision matching typically discards the most data because it requires finding pairs of subjects that match exactly or almost exactly on certain variables, which can be difficult to achieve, leading to the exclusion of many potential subjects.

Question 6

Two Matched Groups Alex matched subjects with adjacent locus of control scores.She used ____ matching.

Accepted Answer

Rank-ordered matching involves matching individuals based on their rank within the distribution of a specific trait, such as locus of control scores. This ensures that the groups are well-matched on that specific trait, reducing the potential for confounding variables.

Question 7

Two Matched Groups If the matching variable is not highly correlated with the dependent variable,

Accepted Answer

If the matching variable is not highly correlated with the dependent variable, the chances of detecting the effect of the experimental manipulation may be reduced. This is because the matching variable is used to control for individual differences between the two groups, and if it is not strongly related to the outcome variable, then it may not effectively eliminate these differences. Therefore, the best choice is C.

Question 8

Two Matched Groups Which of these designs does the best job of controlling extraneous subject variables?

Accepted Answer

Two matched groups design does the best job of controlling extraneous subject variables by matching participants based on relevant variables and then randomly assigning one of the matched pairs to the experimental group and the other to the control group. This reduces individual differences between groups, making it easier to isolate the effect of the independent variable.

Question 9

Two Independent Groups In psychotherapy research, ____ are often used as control groups.

Accepted Answer

The answer of Two Independent Groups In psychotherapy research, ____...

Question 10

Two Matched Groups Dexter formed matched pairs when systolic blood pressures fell within 5 mm Hg.Which form of matching did he use?

Accepted Answer

Range matching involves grouping subjects whose values fall within a specified range, such as 5 mm Hg for blood pressure in this case.

Question 11

Two Independent Groups All of these statements accurately describe random assignment except:

Accepted Answer

Random assignment does not guarantee that the groups will be comparable in every aspect; it simply ensures that each participant has an equal chance of being assigned to any group, which helps to control for systematic differences. Differences between groups can still occur by chance.

Question 12

Two Matched Groups In a two matched groups design, the matching variable should be highly correlated with the ____ variable.

Accepted Answer

In a two matched groups design, the matching variable is used to pair participants in a way that controls for variability in the dependent variable. This ensures that any differences observed between groups can be more confidently attributed to the manipulation of the independent variable, rather than to pre-existing differences between participants. Matching is thus directly aimed at reducing variability in the dependent variable by equating groups on certain characteristics.

Question 13

Two Matched Groups Will created matched pairs of subjects with identical weights in a study comparing the effectiveness of low-carbohydrate and Mediterranean diets in reducing triglycerides.He used ____ matching.

Accepted Answer

Precision matching involves pairing subjects based on very specific criteria, such as identical weights, to ensure that the matched pairs are as similar as possible in the aspect being controlled for, in this case, their weight.

Question 14

Two Matched Groups Matching is invaluable to researchers because it

Accepted Answer

Matching helps to increase the chance of detecting the effect of the experimental manipulation by creating two groups that are similar in all relevant aspects except for the variable being manipulated. This allows for a better comparison between the two groups and a clearer determination of the effect of the manipulation. Matching does not eliminate the need for a control group, produce a normal distribution of scores, or reduce the number of scores that must be discarded.

Question 15

Two Matched Groups Critics have challenged the internal validity of Brady's (1958) study of ulcers in monkeys.Select the design that allows us to compare "executive" and "nonexecutive" monkeys and prevents selection threat.

Accepted Answer

The two matched groups design is the best choice as it allows for the comparison of "executive" and "nonexecutive" monkeys while also preventing selection threat. In this design, the two groups are matched based on relevant variables (such as age, sex, and baseline health status) in order to control for extraneous variables that could affect the outcome. This helps to increase internal validity by ensuring that any differences observed are likely due to the treatment (being an executive monkey) rather than other factors.

Question 16

Two Matched Groups In Jason's study of the effect of the magnitude of reward, he randomly assigned dogs to groups that received one, two, or three cubes of cheddar cheese as reward and measured the time it took each group to complete a tracking course over five trials.Which design did he use?

Accepted Answer

Jason's study involves multiple independent groups, each receiving a different level of the independent variable (amount of cheese).

Question 17

Two Independent Groups Which experimental design raises the fewest ethical concerns in drug research that involves actual patients?

Accepted Answer

Comparing a new drug against a standard treatment raises the fewest ethical concerns because it ensures that all participants receive some form of treatment, avoiding the ethical issue of withholding treatment from patients in need.

Question 18

Two Matched Groups Matching procedures are especially useful when we have small numbers of subjects because

Accepted Answer

Matching procedures help to ensure that the groups in an experiment are similar on important variables that could potentially affect the outcome of the study. Random assignment does not guarantee that the groups will be similar, especially in small sample sizes. Matching can therefore increase the internal validity of the study by reducing the likelihood of confounding variables. However, matching does not necessarily increase the external validity of an experiment, nor does it produce a normal distribution of scores. Random assignment can still be used in small sample sizes, but it may not be as effective in creating similar groups as matching procedures.

Question 19

Two Matched Groups The ____ design is the most commonly used multiple groups design.

Accepted Answer

The multiple independent groups design is the most commonly used multiple groups design as it allows for comparison across different groups with different participants in each group.

Question 20

Two Matched Groups Which matching procedure consistently creates groups that are most alike on the matching variable?

Accepted Answer

Precision matching involves matching individuals on a continuous measure with a specified level of precision, such as matching individuals within a certain range of scores. This creates groups that are more similar on the matching variable than other matching procedures, such as interval matching (which only matches individuals within specified intervals) or rank-ordered matching (which matches individuals based on their rank on the matching variable, rather than their actual scores). Range matching may also create similar groups, but it is less precise than precision matching. Therefore, B) precision matching consistently creates groups that are most alike on the matching variable.

Quiz 9: Basic Between-Subjects Designs