PSY 211 Exam 1

The mean of the standard normal distribution of ... and the standard deviation is ...

0,1

the mean of the standard normal distribution of ... and the standard deviation is..

0;1

The standard deviation for the sample numbers 8,9,&10 is

1.0

If we have data that have been sampled from a population that is normally distributed with a mean of 50 and a standard deviation of 10, we would expect that 95% of our observations would lie in the interval that is approximately

30-70

If you double all the scores in a distribution, the new variance will be .... times greater than the original variance

4

if the 40th percentile on an examination is 75.5, then

40% of the people got a score of 75.5 or less

If the 40th percentile in an exam was 72, then...

40% of the people scored at 72 or below

What percentage of scores is below the mean in a normal distribution?

50%

A z-score of 0.00 corresponds to the ... percentile

50th

A z-score of 0.00 is equal to the ... percentile

50th

which of the following is the best interpretation of the 80th percentile?

80% of the scores fall equal to or below the 80th percentile

A test score of 84 was transformed into a standard score of -1.5. If the standard deviation of test scores was 4, what is the mean of test scores?

90

Which situation could be considered an outlier?

A $50 million per year salary in the us

Which of the following is a continuous variable?

Age

The variance will equal zero when

All the scores are the same

If happiness could be measured using a ratio scale, a score of zero would mean

An absence of happiness

The variance can best be thought of as the

Average of the squared deviations from the mean

If a researcher is measuring driving speed and two non adjacent driving speeds occur the most with equal frequency, the distribution is

Bimodal

Is speed a continuous or discrete variable

Continuous

An individual' yearly salary would be measured on a ... scale and the number of cars that the individual owns would be measured on a ... scale.

Continuous, discrete

Is the number of academic degrees earned a continuous or discrete variable?

Discrete

The scale used to measure the number of dogs you have would be measured on the ... scale, and the scale used to measure the length of time it takes you to run 2 miles would be measured on the ... scale

Discrete; continuous

Which of the following would come closest to recruiting a random sample of college students?

Drawing 50 telephone numbers from a hat containing the phone numbers of all students

If a score that is 1 standard deviation above the mean is transformed in to a z-score, the new score will be

Exactly 1 standard deviation above the mean

A normal distribution can be bimodal

False

Class rank of a student is an example of a continuous variable

False

Gender is primarily used as a dependent variable

False

Suppose we measure attitudes toward the new Walmart in Athens on a 1 (do not like) to 9 (like very much) scale. we can conclude that someone who circles '8' on this scale likes Walmart twice as much as someone who circles '4'

False

The z-score distribution is an example of the ratio scale of measurement

False

Salaries in the us is negatively skewed

False in a positively skewed distribution the value for the median will be greater than the value for the...

In a grouped frequency distribution, what does the cumulative frequency measure?

Frequency of all scores at or below a particular point

Random sampling is important when a researcher wants to

Generalize from a sample to population

If a population of scores ranges from 1 to 100, with a mean of 60 and a mode of 80, what is true about the distribution

It is a negatively skewed distribution

According to the text book, if a PSY211 instructor uses scores from her class on Exam #1 to generalize to all PSY211 students at CMU, the instructor is,

Making a statistical inference

Inferential statistics are primarily concerned with:

Making inferences about a population from a sample

In psychological research, An independent variable is ... and a dependent variable is ...

Manipulated, measured

Which measure of central tendency is most effected by a single outlier?

Mean

If a store manager wanted to stock the men's clothing department with shirts fitting the most men, which measure of central tendency of men's shirt sizes should we use?

Mode

In a positively skewed distribution the value for the median will be greater than the value for the...

Mode

The median is greater than the ... in a positively skewed distribution

Mode

Which measure of central tend you can be used for nominal data?

Mode

A normal distribution can

Only be unimodal and symmetrical

The value of the single, smallest score in a distribution of scores is 25. If that score is changed from 25 to 10, which measure of central tendency is absolutely certain to change

Only the mean is certain to change

In the Olympic Games, what type of scale is represented by gold, silver and bronze medals?

Ordinal

Official rank in the military is an example of which scale of measurement

Ordinal

What two parameters completely characterize a standardized normal distribution?

Pop. Mean & pop. Standard deviation

What is the primary difference between an interval and a ratio scale of measurement

Ratio has an absolute zero

The degree of asymmetry in a distribution is called

Skewness

If you multiplied each student's score (number of times they visited the zoo) by 2, what would happen to the new standard deviation when compared to the original standard deviation?

The new standard deviation would be twice as large

If we repeatedly sample from a single population, which of the following will be the most stable?

The sample mean

A normal distribution is always unimodal and symmetrical

True

A variance can equal zero

True

Birth order is a good example of the ordinal scale of measurement

True

Class rank is an example of a categorical variable

True

The degree to which individual data points are distributed around the mean indicates ... in the data

Variability

If we discover in a distribution p=0, which of the following is true:

We are using a parameter

If we discover in a distribution that p=2, which of the following is true:

We are using a parameter

when a distribution has two separate and distinct medians, then

a distribution can never have more than one median

the relation between a sample and a statistic is the same as the relation between

a population and a parameter

when the variance is equal to zero...

all of the raw scores are the same

which of the following is not a discrete variable? number of bars a shuttle group visited; number of tables available; amount of time they stayed in a bar; number or people who passed out

amount of time they stayed in a bar

The scale used to measure the tin is?

continuous

amount of verbal material learned in 30 minutes (discrete or continuous)

continuous

number of children in a family (discrete or continuous)

discrete

σnew=σold÷C

dividing standard deviation by a constant

σ²new=σ²old÷C²

dividing variance by a constant

if a score that is 1 standard deviation above the mean is transformed into a z-score, the new score will be

exactly 1 standard deviation above the mean

a distribution of scores has a mean=30, median=20, and mode=10. The distribution:

has a positive skew

the concept of generalizing from a few observations to an entire group is central to the area of:

inferential statistics

which is the most commonly used measure of central tendency

mean

adding a constant mean new= mode new= median new=

mean old + C mode old + C median old + C

subtracting a constant mean new= mode new= median new=

mean old - C mode old - C median old - C

multiplying constant mean new= mode new= median new=

mean old X C mode old X C median old X C

When constructing histograms from a grouped frequency distribution, what should be used to denote the points on the scale of measure?

midpoint

σnew=σold×c

multiplying standard deviation by a constant

σ²new=σ² old × c²

multiplying variance by a constant

numbers used to identify political affiliation (what scale of measurement)

nominal

social security number (what scale of measurement)

nominal

class rank (what scale of measurement)

ordinal

students voted for their professors by ranking them. this is an example of measurement on a .... scale

ordinal

what scale of measurement is used if you know that one variable is larger than another, but you do not know how much larger?

ordinal

σ=√σ²

population standard deviation

σ²= (∑(X-µ)²)÷N

population variance

not everything naturally follows a normal distribution, such as salaries in the US. The distribution of salaries in the US is

positively skewed because rich people represent outliers who earn significantly more than everyone else

What type of scale would be used to measure the tin?

ratio

amount of time it takes a pain relieve to work (what scale of measurement)

ratio

length or width of a room (what scale of measurement)

ratio

s=√s²

sample standard deviation

s²= (∑(X-X⁻)²)÷n-1

sample variance

the median is equivalent to

the 50th percentile

The interquartile range is not the best measure of dispersion because it eliminates 50% of the distribution. The 50% of the distribution that is eliminated is:

the lower 25% and the upper 25%

the value of one score in a distribution is changed from X=20 to X=30. Which measure of central tendency is/are certain to be changed?

the mean

if a distribution has a positive skew, which of the following is true

the median will greater than the mode

a survey asks whether participants think OJ is innocent or guilty. Which would be the best measure of central tendency to describe this data set?

the mode

the only measure of central tendency we are certain to actually observe as a value in our data set is

the mode

how does it affect the mean when you add a constant to every score?

the new mean will be 5 points higher than the old mean

how is the standard deviation affected when you divided a constant into every score?

the new standard deviation will be half the size (twice as small) as the old standard deviation

how does it affect the standard deviation when you divide a constant into every score?

the new standard deviation will half the size as the old standard deviation

how does it affect the variance when you subtract a constant from every score?

the new variance and the old variance will be the same

adding/ subtracting does not change the..... & ......

variance and standard deviation