Psy 281 exam s2 study guide #3

a significant result in a one sample t test (p<0.05) means:

There is a significant difference between the sample and population mean

a two sample t test is used to

Compare the means of two independent groups

The null hypothesis (h^0) in a two sample t test usually states that

The two population means are equal

Which of the following is an assumption of the independent samples t test

The variances of the two groups are approximately equal

a two tailed test is used when

we are interested in whether the two means are different, regardless of direction

The main advantage of a repeated measures design is that it

reduces individual differences

a within subjects design is also known as

a repeated measures design

a repeated measures design is sometimes called

a within subjects design

in a within subjects design, each participant

takes part in all experimental conditions

a paired sample t test is used to

compare the means of the same group measured twice

another name for a paired sample t test is

dependent samples t test

The null hypothesis (H^0) states that

The mean difference between pairs equals zero

Which of the following best describes when to use a paired sample t test

The same participants are tested before and after an intervention

A data set with a large standard deviation compared to another dataset has

Values more spread out from the mean

Two bellshaped histograms are shown, graph A is tall and narrow, graph B is short and wide. Which graph has the larger standard deviation? 

Graph B

In a survey, a Likert scale item says: “I feel unhappy most of the time”(1=strongly disagree, 5= strongly agree). If we want to make sure a higher score means “more happiness” what should be done. 

reverse code of responses

A participant responds “4” (agree) to the negatively worded item “I often feel nervous” if the scale is 1-5 and the item is reverse coded, what is the recoded score? 

2

Which of the following statements about reversing scoring is false?

Reverse scoring changes the actual meaning of participants responses

what does variability describe

how spread out or different the scores are

If every person in a group receives exactly the same score, what is the standard deviation

0

why is standard deviation useful

it tells us how spread out scores are around the mean

Two groups have the same mean happiness score of 50. Group A has SD=2 and Group B has SD=12. What can we conclude?

Happiness scores vary more among people in group B

What does the central limit theorem primarily describe

the distribution of sample means

According to the central limit theorem if we repeatedly take sufficiently large random samples from a population, the distribution of the sample means tends to become 

Normal

the distribution created by taking many samples means is called the

sampling distribution of the mean

the mean of the sampling distribution will be approximately equal to

the population mean