Psych 100a Practice Test

Which of the following is a continuous variable?

The number of people in a household

Speed in miles per hour

Shoe size

Placements in a competition (1st, 2nd, 3rd, etc.)

Speed in miles per hour

Which of the following is a discrete variable?

Response time

GPA

Gender

Weight

Gender

Which of the following variables is measured on an ordinal scale (i.e., an ordinal variable)?

Number of days spent in hospital

Competition placing (Gold, Silver, Bronze)

Political party affiliation (Republican, Democrat, Independent, etc.)

Response time

Competition placing (Gold, Silver, Bronze)

Which of the following variables is measured on a nominal scale (i.e., a nominal variable)?

Type of living accommodation (House, Apartment, Trailer)

Doctor-reported health level (poor, fair, good, excellent)

Celsius temperature

Education level

Type of living accommodation (House, Apartment, Trailer)

Which of the following variables is measured on a numeric scale (i.e., a numeric variable)?

Major

Ethnicity

Year in College (e.g., freshman, sophomore etc.)

Price of dining hall meal

Price of dining hall meal

A study interested in the effect of students' perceived utility of the course on their course performance asked students at the beginning of the quarter how useful they think the course is going to be.

Students indicated their perceived utility of the course using a 5-point Likert-type rating scale ranging from 1 ("Not useful at all") to 5 ("Extremly useful"). Which level of measurement describes this variable?

Quasi-Interval

Interval variable

Nominal variable

Quasi-Interval

A researcher is interested in studying the effects of sleep on college students' grades in the United States. Thus, this researcher collected responses from a total of 100 UCLA students in order to assess whether sleep affects the grades of college students.

What is the sample in this research?

100 college students at UCLA

College students across the world

College students in the United States

All college students at UCLA

100 college students at UCLA

A researcher is interested in studying the effects of sleep on college students' grades in the United States. Thus, this researcher collected responses from a total of 100 UCLA students in order to assess whether sleep affects the grades of college students.

What is the population in this research?

College students in the United States

All college students at UCLA

100 college students at UCLA

College students across the world

College students in the United States

True or false? Nominal and ordinal variables can be discrete, but interval and ratio variables cannot be discrete.

True

False

False

Which of the following variables is considered to be a continuous variable?

Blood type

Self-reported health (poor, fair, good, excellent)

Type of living accommodation (House, Apartment, Trailer)

SAT scores

SAT scores

A researcher asks you to report the number of minutes that you studied for your stats class yesterday. In this case, the researcher is measuring the variable of studying on a(n) ___________ scale.

Nominal

Quasi-Interval

Ordinal

Ratio

Ratio

In a frequency distribution, which quantity describes the number of respondents providing a particular response?

Percent (% of total)

Count (Frequency)

Cumulative percent (cumulative %)

Count (Frequency)

Which of the following frequency tables is correct?

2

Consider the following frequency distribution for a survey question asking about the participants’ highest level of education (the Frequency column is the same as the Count).  What is the value for the percent in the cell labeled X?

83

A study explored the effectiveness of a new mindfulness intervention in terms of stress reduction. They found that the distribution of stress levels of all participants in the study is left skewed. What does this distribution of stress level look like?

 

More participants are under low levels of stress and less participants are under high levels of stress

 

There are even numbers of participants for each level of stress

 

More participants are under high levels of stress and less participants are under low levels of stress

More participants are under high levels of stress and less participants are under low levels of stress

A dog food company tests whether dogs like a new flavor of dog food. They measure how many ounces of food each dog eats. If they want to display the distribution of the ounces eaten from 100 dogs in a figure, which figure(s) should they use? Select all that apply.

 

Bar plot

 

Density plot

 

Histogram

 

Frequency distribution table

Density plot

 

Histogram

In a biology class, the distribution of students’ grades is in the Table. The professor writes an exam for her class of 100 students. What is the proportion of students getting a C or higher? Answer: __% (do not include percent sign in your answer, just type the number)

96

A researcher for an ice cream company has a sample of customers taste three flavors of ice cream: vanilla, chocolate, and strawberry. After they taste the flavors, the researcher asks each customer which flavor was their favorite, and then she records the flavor each person said they liked the most. If the researcher wants to display the distribution of the customers’ responses in a figure, what should she use? Select all that apply.

 

Bar plot

 

Histogram

 

Frequency distribution table

 

Density plot

Bar plot

Frequency distribution table

If a distribution is flatter than a normal distribution, the kurtosis is

 

negative

 

We don't know

 

positive

 

zero

negative

If a distribution is negatively skewed, the kurtosis is

 

negative

 

positive

 

We don’t know

 

zero

We don’t know

If a distribution is negatively skewed, the skewness is

 

zero

 

negative

 

We don’t know

 

positive

negative

The higher the density, the:

 

more often/likely it is to observe some value

 

higher the kurtosis

 

lower the kurtosis

 

less often/likely it is to observe some value

more often/likely it is to observe some value

Which of the following are symmetric distributions? Select all that apply. 

 

Uniform Distributions

 

Distributions with kurtosis of 0

 

Right-skewed distributions

 

Normal Distributions

 

Left-skewed distributions

Uniform Distributions

Normal Distributions

When a distribution has skewness above 2, which of the following is true?

 

It is negatively skewed

 

It also has a kurtosis above 2

 

It is left-skewed

 

It is right-skewed

It is right-skewed

A study of post-partum depression found a relatively even number of mothers with low, moderate, and high depression levels.  What distribution shape best describes the depression variable?

 

Positively skewed

 

Uniform

 

Normal

 

Negatively skewed

Uniform

Which statement correctly describes how categories should be ordered when displaying nominal and ordinal variables in a bar plot?

 

Categories can be arranged arbitrarily for nominal variables, but ordinal variables should preserve their meaningful order

 

Categories can be arranged arbitrarily for ordinal variables, but nominal variables should preserve their meaningful order

 

Categories must be ordered for both nominal and ordinal variables

 

Categories can be arranged arbitrarily for both nominal and ordinal variables

Categories can be arranged arbitrarily for nominal variables, but ordinal variables should preserve their meaningful order

What kind of study is this: Comparing sleep habits and GPA

Observational study

Between-group design

Within-group design

Observational study

What kind of study is this: Coffee group v.s. Water group

Observational study

Between-group design

Within-group design

Between-group design

What kind of study is this: Anxiety before v.s. after finals

Observational study

Between-group design

Within-group design

Within-group design

Consider the first item, Item1, which ranges from 1 (Strongly Disagree) to 6 (Strongly Agree). What level of measurement describes the Item1 variable? Select all that apply.

 

Nominal

 

Ordinal

 

Numeric

 

Quasi-interval

 

Interval

Ordinal

Quasi-interval

What level of measurement describes the scale score variable?

 

Nominal

 

Ordinal

 

Numeric

Numeric

Consider the following set of depression scores: 7,10,10,12,31,38

1. What is the sample mean?

2. What is the sample median?

3. What is the sample mode?

18, 11, 10

Considering the frequency distribution below:

What response category corresponds to the mode?

 

Disagree

 

Strongly disagree

 

Strongly Agree

 

Agree

 

Neither agree nor disagree

Disagree

What response category corresponds to the median?

 

Strongly disagree

 

Strongly Agree

 

Neither agree nor disagree

 

Disagree

 

Agree

Neither agree nor disagree

A researcher wants to use a measure of central tendency to summarize the political party breakdown of his sample.  Which measures of central tendency can be computed for this variable?  Note that the question is NOT asking which one you should use, but which one you COULD use as a REASONABLE measure. Check ALL that apply.

 

Mode

 

Median

 

Mean

Mode

A researcher is studying the distribution of number of pets per family and she wants to report the central tendency for this distribution.  Which measures of central tendency can be computed for this variable?  Note that the question is NOT asking which one you should use, but which one you COULD use as a REASONABLE measure. Check all that apply.

 

Mean

 

Mode

 

Median

Mean

 

Mode

 

Median

A researcher is studying the distribution of academic letter grades (i.e., A, B, C, and D) in a college and she wants to report the central tendency for the academic letter grades.  Which measures of central tendency can be computed for this variable?  Note that the question is NOT asking which one you should use, but which one you COULD use as a REASONABLE measure. Check all that apply.

 

Mode

 

Mean

 

Median

Mode

Median

With what types of variables can the mean be used? Check all that apply.

 

Nominal

 

Numeric

 

Ordinal

Numeric

With what types of variables can the mode be used? Check all that apply.

 

Ordinal

 

Nominal

 

Numeric

Ordinal

 

Nominal

 

Numeric

A researcher obtains the mean, median, and mode for his data. The mean, median, and mode all equal 10. Based on these descriptive statistics, how is this data likely to be distributed?

 

Positively skewed

 

Symmetric distribution

 

Negatively skewed

Symmetric distribution

A researcher obtains the mean, median, and mode for his data. The mean is 10, median is 12, and mode is 20. Based on these descriptive statistics, how is this data likely to be distributed?

 

Symmetric distribution

 

Positively skewed

 

Negatively skewed

Negatively skewed

A researcher’s sample mean equals 20. If the true mean in the full population is 18, what is the sampling error?

2

Which best describes the sample mean?

 

The sample mean is the sum of the data divided by the number of data in the sample.

 

The sample mean is the number of data in the population divided by the sum of the data.

 

The sample mean is the number of data in the sample divided by the sum of the data.

 

The sample mean is the sum of the data divided by the number of data in the population.

The sample mean is the sum of the data divided by the number of data in the sample.

Because we can’t always calculate the parameter of a statistic, we often need to calculate the estimate of a statistic instead.

 

True

 

False

True

A sample mean is a/an ______. A population mean is a/an ________.

 

Estimate/parameter

 

Measure of central tendency/measure of variability

 

Measure of variability/measure of central tendency

 

Parameter/estimate

Estimate/parameter

For which of the following data sets is the mode equal to the median?

 

2, 3, 4, 5, 5, 6

 

1, 1, 1, 3, 3, 3

 

1, 19, 20, 21, 40, 40

 

3, 4, 4, 4, 5, 10

3, 4, 4, 4, 5, 10

When sample size increases:

 

Sampling error generally is biased

 

Sampling error generally increases

 

Sampling error generally decreases

 

Sampling error generally stays the same

Sampling error generally decreases

In a negatively skewed distribution, we would expect...

 

The mean to be larger than the median and the median to be larger than the mode

 

The mean to be smaller than the median and the median to be smaller than the mode

 

The mean, median, and mode to be roughly equal

The mean to be smaller than the median and the median to be smaller than the mode

In the above image, the mean of each distribution is represented by the letter ____.

A

In the above image, the median of each distribution is represented by the letter ____.

 

A

 

C

 

B

B

In the above image, the mode of each distribution is represented by the letter ____.

 

C

 

B

 

A

C

True or false: Sampling error can be either positive or negative.

 

False

 

True

True

A UCLA professor is interested in studying the height of college students in California. Somehow, she knows that the true population mean is 67 inches. The mean height of students in her Psych 100A class is 68 inches. She then goes to USC and finds the mean height of their 100A class. Which of the following is true about the sampling error of the USC 100A class?

 

It could be positive or negative

 

It will be negative, because it must average out to 67 inches

 

It will also be positive, like the UCLA class

 

It will be positive, because all sampling errors will be positive

It could be positive or negative

Consider the following set of scores: 5, 5, 6, 7, 7, 8, 10, 12, 15, 19. What is the mode of this distribution?

 

5

 

5 and 7

 

7.5

 

8

5 and 7

A statistician records the number of hours five athletes exercise each week: 2, 3, 3, 4, and 5. The highest recorded value is corrected from 5 to 25 hours. Which of the following is true?

 

Neither the mean nor median changes

 

The median increases, but the mean stays the same

 

Both the mean and median increase

 

The mean increases, but the median stays the same

The mean increases, but the median stays the same

Suppose the sample standard deviation in Question 3 is A and the sample variance in Question 4 is B. Which of the following interpretations is correct regarding the standard deviation and variance (assuming a normal distribution)? Check all that apply.

 

a) All scores are within ± A points of the mean

 

b) All scores are within ± B points of the mean

 

c) The average difference between an individual’s score and the mean is A

 

d) The average squared difference between an individual’s score and the mean is B

 

e) 68% percent of the CLAUSTROPHOBIA scale scores fall between ± A points of the mean

c) The average difference between an individual’s score and the mean is A

 

d) The average squared difference between an individual’s score and the mean is B

 

e) 68% percent of the CLAUSTROPHOBIA scale scores fall between ± A points of the mean

If the population standard deviation increases and the sample size stays the same, what will happen to the sampling error and standard error? Check all that apply.

 

a) Standard error will increase

 

b) The average amount of sampling error will increase

 

c) The average distance between sample means and the population mean will increase

 

d) The standard deviation of the sampling distribution will increase

a) Standard error will increase

 

b) The average amount of sampling error will increase

 

c) The average distance between sample means and the population mean will increase

 

d) The standard deviation of the sampling distribution will increase

If one participant’s CLAUSTROPHOBIA score has a z score of 0.2, which of the following interpretations is correct?

 

a) This participant’s score is 0.2 points higher than the mean of CLAUSTROPHOBIA

 

b) This participant’s score is 0.2 sampling errors higher than the mean of CLAUSTROPHOBIA

 

c) This participant’s score is 0.2 standard deviations higher than the mean of CLAUSTROPHOBIA

c) This participant’s score is 0.2 standard deviations higher than the mean of CLAUSTROPHOBIA

In which group are claustrophobia scores most similar?

 

a) Males

 

b) Females

a) Males

The Cohen’s d (standardized mean difference) effect size value is 1.18. Which of the following interpretations is correct about this value?

 

a) The treatment and control groups differ by 1.18 points

 

b) The mean difference between the treatment and control group explains 118% of the variation (individual differences) in claustrophobia levels

 

c) The treatment and control group means differ by 1.18 standard deviation units

 

d) The treatment group’s effect is 1.18 times as large as the effect of the control group

c) The treatment and control group means differ by 1.18 standard deviation units

When is Cohen’s d negligible

less than |0.20|

When is Cohen’s d small

|0.20 to 0.50|

When is Cohen’s d moderate

|0.50 to 0.80|

When is Cohen’s d large

greater than |0.80|

Considering the raw mean values and the standardized mean difference, which of the following interpretations is correct?

 

a) Females have higher levels of claustrophobia, and the sex difference is negligible

 

b) Females have higher levels of claustrophobia, and the sex difference is small in magnitude

 

c) Females have higher levels of claustrophobia, and the sex difference is moderate in magnitude

 

d) Females have higher levels of claustrophobia, and the sex difference is large in magnitude

a) Females have higher levels of claustrophobia, and the sex difference is negligible

Considering the raw mean values and the standardized mean difference, which of the following interpretations is correct? Apply Cohen’s effect size benchmarks from the lecture slides.

 

a) The treatment group has a lower level of claustrophobia, and the mean difference is small in magnitude

 

b) The treatment group has a lower level of claustrophobia, and the mean difference is moderate in magnitude

 

c) The treatment group has a lower level of claustrophobia, and the mean difference is large in magnitude

 

d) The control group has a lower level of claustrophobia, and the mean difference is small in magnitude

 

e) The control group has a lower level of claustrophobia, and the mean difference is moderate in magnitude

 

f) The control group has a lower level of claustrophobia, and the mean difference is large in magnitude

c) The treatment group has a lower level of claustrophobia, and the mean difference is large in magnitude

A researcher summarized the descriptive statistics for pain scores in her study comparing a new pain medication (treatment group) to a placebo (control group). A higher score in her questionnaire reflects a higher level of pain. The results indicate that the sample mean of the treatment group was 80 and the sample standard deviation was 10. The sample mean of the control group was 75 and the sample standard deviation was 12. In which group are pain scores most similar to one another?

 

Control group

 

Treatment group

Treatment group

In a normal distribution with a mean of 60 and a standard deviation of 10, which of the following interpretations is definitely true?

 

The average squared difference between a score and the mean is 10 points

 

The difference between the lowest and highest score is 20

 

All scores are within ± 10 points from the mean

 

68% of scores are within ± 10 points from the mean

 

All scores are within ± 20 points from the mean

 

95% of scores are within ± 20 points from the mean

68% of scores are within ± 10 points from the mean

 

95% of scores are within ± 20 points from the mean

A researcher is summarizing a sample of ages and reports that the average difference between a respondent’s age and the sample mean is 8 years.  Which measure of variability is she reporting?

 

Standard deviation

 

Sum of squares

 

Variance

 

Deviation score

Standard deviation

A researcher summarizes a sample of income scores and reports that the average squared difference between a respondent’s income and the sample mean is 10,000.  Which measure of variability are they reporting?

 

Variance

 

Deviation score

 

Sum of squares

 

Standard deviation

Variance

The population standard deviation formula has N in the denominator, whereas the sample standard deviation formula has N-1 in the denominator. What is the rationale for using N-1 rather than N?

 

We don't know the number of observations in the full population, so we use N-1 as an estimate of the number of observations

 

Dividing by N would make the sample standard deviation a more accurate estimate of the population standard deviation

 

We don’t know the population mean and hence use the sample mean as a replacement. As a consequence, the sum of squares tends to be too small. N-1 is used to counteract the effect from the small sum of squares.

We don’t know the population mean and hence use the sample mean as a replacement. As a consequence, the sum of squares tends to be too small. N-1 is used to counteract the effect from the small sum of squares.

If a participant in a study obtained a score of 90 but the mean is 100, then what is the deviation score for this participant?

-10

__________ describes the relation between sample mean and the population mean,
as __________ describes the relation between individual score and sample mean (or
population mean).

 

standard deviation, variance

 

standard deviation, sampling error

 

sampling error, standard deviation

 

variance, standard deviation

sampling error, standard deviation

As sample size increases, sampling error generally:

 

increases

 

we don't know

 

stays the same

 

decreases

decreases

A researcher calculates the standard deviation of salaries and obtains a value of zero. Which of the following is true?

 

A mistake was made, the standard deviation cannot equal zero

 

All salaries were identical

 

Salaries were normally distributed around the mean

 

No answer text provided.

All salaries were identical

In the above image, which distribution has the greater standard deviation?

 

Neither—we do not have enough information

 

Neither—both distributions have the same standard deviation

 

The purple distribution

 

The red distribution

The red distribution

In the above image, which distribution has the higher variance?

 

The red distribution

 

The purple distribution

 

Neither—we do not have enough information

 

Neither—both distributions have the same variance

The red distribution

When we calculate a sample standard deviation, we divide by N-1, not N. What would happen if we divided by N instead?

 

The estimate would be too small

 

The parameter would be too small

 

The estimate would be too large

 

The parameter would be too large

The estimate would be too small

A researcher calculates each participant’s deviation from the sample mean and then averages those deviation scores. The result is zero, even though participants have different scores. Why does this happen, and how does calculating variance address it?

 

All participants have identical scores; variance identifies differences between them.

 

The sample is too small; variance increases the number of participants.

 

The mean is incorrect; variance replaces it with the median.

 

Positive and negative deviations cancel; variance uses squared deviations to prevent this cancellation.

Positive and negative deviations cancel; variance uses squared deviations to prevent this cancellation.

A department has 40 faculty members. A researcher obtains salary information for all 40 and calculates their standard deviation. Her population of interest is the faculty in this department. How should this standard deviation be classified?

 

A population parameter, because it was calculated using the entire population of interest

 

A deviation score, because it describes differences in salaries

 

Sampling error, because salaries differ across faculty members

 

A sample estimate, because 40 is a small number of people

A population parameter, because it was calculated using the entire population of interest

A researcher measures participants’ ages in years and obtains a variance of 25 years squared. What is the standard deviation, and why is it easier to interpret than the variance?

 

5 years, because it expresses spread in the original units of age

 

25 years, because variance and standard deviation have the same numerical value

 

5 years squared, because it retains the units of variance

 

625 years, because standard deviation is the square of variance

5 years, because it expresses spread in the original units of age

In a negatively skewed distribution, a student obtains a test score below the mean. What do we know about this student’s z-score?

 

The z-score is positive

 

The z-score is negative

 

The z-score is zero

 

The z-score could be positive or negative

The z-score is negative

Researchers are interested in studying factors related to teenage drinking frequency (higher scores = more frequent drinking). In particular, the researchers want to determine whether growing up with an alcoholic parent versus not has an influence on the frequency of drinking. A researcher found a standardized mean difference effect size of -0.9 (non-alcoholic minus alcoholic).  How would you characterize the impact of growing up with an alcoholic parent in this study?

 

Growing up with an alcoholic parent had a small positive impact on drinking frequency

 

Growing up with an alcoholic parent had a moderate positive impact on drinking frequency

 

Growing up with an alcoholic parent had almost no impact on drinking frequency

 

Growing up with an alcoholic parent had a large positive impact on drinking frequency

Growing up with an alcoholic parent had a large positive impact on drinking frequency

A researcher is summarizing a sample of happiness scores (which are on a scale from 1 to 100). She reports that the sample mean is 60 and the sample standard deviation is 5.  If a respondent’s happiness score is 65, what is their corresponding Z score (keep no decimals)?

1

Researchers are interested in the effect of a smoking cessation intervention.  Before the intervention, the number of smoked cigarettes per week was recorded for each participant. After the intervention, participants smoked less cigarettes, with a standardized mean difference of -2. Which of the following interpretations is correct?

 

The number of smoked cigarettes decreases by 2 cigarettes after the intervention

 

The number of smoked cigarettes decreases by about 2 standard deviations after the intervention

 

The number of smoked cigarettes decreases by about 2% of a standard deviation unit after the intervention

The number of smoked cigarettes decreases by about 2 standard deviations after the intervention

One researcher is interested in the treatment effects of two depression interventions. There are three groups: control group, Intervention A, and Intervention B. Both interventions decreased the depression level scores of  participants. Intervention A provides a standardized mean difference of 0.6 (relative to the control), and Intervention B provides a standardized mean difference of 0.5 (relative to the control).  Which intervention was most effective at reducing depression symptoms?

 

Intervention A

 

Intervention B

Intervention A

A researcher transformed her variable of interest, Depression, to a z-score. She names this z-score variable, Z-Dep. She plots both the Z-Dep and the Depression variables in jamovi. What can she expect from these plots?

 

The shape of the distributions will be the same because z-score transformations do not alter the shape of the original distribution.

 

The shape of the distributions will be different; however, we cannot be sure exactly how the distribution shapes will differ.

 

The shape of the distributions will be different, and you are able to calculate the transformation by using the z-score formula.

The shape of the distributions will be the same because z-score transformations do not alter the shape of the original distribution.

A high school math teacher gave their class an exam. The mean grade on the exam was 90 with a standard deviation of 2. The teacher converted the students’ grades to z-scores and then shared these scores with their students. One student got a z-score of -1. What can you say about this student’s grade?

 

This student’s grade was 1 point below the mean grade.

 

This student’s grade was 1 point above the mean grade.

 

This student’s grade was 1 standard deviation above the mean grade.

 

This student’s grade was 1 standard deviation below the mean grade.

This student’s grade was 1 standard deviation below the mean grade.

A researcher is interested in the effect of a new teaching method on math performance. Some students are taught with this new method (Intervention group) and some are taught with an older method (Control group). The groups are the same size. Both groups then take an exam. The Intervention group has an average score of 83/100 while the Control group has an average score of 80/100. The average standard deviation across the two groups is 5. How would you describe the groups’ standardized mean difference?

 

Small

 

Large

 

Negligible

 

Moderate

Moderate

In the process of selecting a tutor for your statistics class, you have narrowed down your search to four candidates:  Han, Ben, Egamaria, and Jordan.  Each candidate took a different statistics class and scored 100 points.  The mean and standard deviation for each of these classes were different, however.  Based on the table above, which candidate should you hire as your tutor?  (That is, which candidate would earn the highest standardized score?)

 

Egamaria

 

Han

 

Jordan

 

Ben

Ben

And which candidate would be your absolute last resort?  (That is, which candidate would earn the lowest standardized score?)

 

Egamaria

 

Ben

 

Han

 

Jordan

Han

You have 20 participants’ depression scores, this variable is called Depress. You convert all their scores into z-scores, this variable is called Z-Depress. What is the approximate mean of the Z-Depress variable?

0

You have 20 participants’ depression scores, this variable is called Depress. You convert all their scores into z-scores, this variable is called Z-Depress. What is the approximate standard deviation of the Z-Depress variable?

1

Standard error is larger with a _______ sample size and/or a _______ population variance. Select one:

 

larger, smaller

 

smaller, smaller

 

larger, larger

 

smaller, larger

smaller, larger

A psychologist administers an anxiety questionnaire to 400 college students and obtained a mean anxiety score of 100 with a standard error of the mean equal to 0.2.  What is the sample standard deviation (keep no decimals)?

4

A psychologist studying exam anxiety administers a questionnaire to 100 UCLA college students and obtains a mean anxiety score of 20. Considering the difference between this estimate and the parameter, which of the following statements is true?

 

The sample size determines whether this estimate is higher or lower than the population mean

 

The mean anxiety score in the population could be higher or lower than 20

 

The mean anxiety score in the population must be lower than 20

 

The mean anxiety score in the population must be higher than 20

The mean anxiety score in the population could be higher or lower than 20

A psychologist studying exam anxiety administers a questionnaire to 100 UCLA college students and obtains a mean anxiety score of 20. Another psychologist administers the same exam anxiety questionnaire to 100 USC college students and obtains a mean anxiety score.  Which of the following statements is true?

 

The new mean will be higher than 20

 

The sample size determines whether the new mean is higher or lower

 

The new mean could be higher or lower than 20

 

The new mean will be lower than 20

The new mean could be higher or lower than 20

A psychologist administered an exam anxiety questionnaire to 400 UCLA college students and obtained a mean anxiety score of 25 with a standard error of the mean equal to 0.25. Which of the following interpretations is correct for the standard error? Check all that apply.

 

A sample mean based on N = 400 should differ from the population mean by 0.25, on average

 

The average distance between an anxiety score and the sample mean is 0.25

 

If the researcher took another sample of any size, the mean should change by 0.25, on average

 

The average distance between an anxiety score and the population mean is 0.25

 

The standard deviation of the sampling distribution is 0.25

 

The average size of deviation scores is 0.25

 

The average amount of sampling error is 0.25

 

The standard deviation of the many sample means from samples of size N=400 is 0.25

A sample mean based on N = 400 should differ from the population mean by 0.25, on average

The standard deviation of the sampling distribution is 0.25

The average amount of sampling error is 0.25

The standard deviation of the many sample means from samples of size N=400 is 0.25

A psychologist studying exam anxiety administers a questionnaire to 400 UCLA college students and obtains a mean anxiety score of 25 and a standard deviation of 5.  Which of the following interpretations is correct for this sample standard deviation? Check all that apply.

 

The average distance between an anxiety score and the sample mean is 5

 

The average distance between an anxiety score and the population mean is 5

 

The standard deviation of the sampling distribution is 5

 

The average size of deviation scores is 5

 

The average amount of sampling error is 5

 

If the researcher took another sample of any size, the mean should change by 5, on average

 

A sample mean based on N = 400 should differ from the population mean by 5, on average

 

The standard deviation of the many sample means from samples of size N=400 is 5

The average distance between an anxiety score and the sample mean is 5

The average size of deviation scores is 5

A group of psychologists administered an exam anxiety questionnaire to 1000 colleges in the US (200 students per school) and obtained 1000 means of anxiety scores. They created a histogram (sampling distribution) of the 1000 sample means. Which of the following best describes the likely shape of this distribution?

 

Negatively skewed

 

Uniform distribution

 

Normal distribution

 

Positively skewed

Normal distribution