H355 quiz 2

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What is the weakness of using range?

based on only 2 scores

interquartile range

the range of the middle 50% of the cases

not normal

the two thirds rule does not apply if the distribution is

x-axis

the variable measures first is placed on the

mutually exclusive

these are the result of chance and are independent of each other

S or ó

these symbols are used to represent the standard deviation of the scores of a population.

scattergram

this is a graphic representation of the relationship between two variables.

4.5

what is the IQ range of these scores: 10,10,11,12,13,13,14,14,15

6.5

what is the IQ range of these scores: 5, 5,0,1,2,11,11,11,10,9,7,6,5,5,0,4

biased

a researcher wishes to generalize to all sociology students and uses volunteers in a sociology class as subjects. is the sample biased or unbiased?

normal distribution

about two-thirds of the cases lie within one standard deviation unit of the mean in a

samples of convience

accidental samples

no

according to the 1% guideline should 0.1056 be classified as an unlikely event?

yes

according to the 5% guideline should 0.0446 be classified as an unlikely event?

-3.00

according to this topic, z-scores are seldom lower than what value?

perfect negative relationship

-1.00 indicates a _______ the strongest possible inverse relationship

non directional hypothesis

alternative hypothesis that states that group X on average is different from group y in an unspecified direction.

perfect positive correlation

1.00 indicates- the strongest possible direct relationship

no

an investigator has studied all the girls and boys in a population. she has found a difference between the mean for boys and the mean for girls. is the null hypothesis a viable hypothesis?

computational formula

another formula for standard deviation

approximate 95% rule

approximately 95% of the cases lie within two standard deviation units of the mean in a normal distribution.

how to find the interquartile range

1. put the scores in order from high to low. Then, determine how many scores constitute one quarter of the scores 2. count up from the lowest score the number of scores you calculated in step 1. 3. count down from the highest score the number of scores you calculated in step one. 4. subtract the answer to step 2 from the answer to step 3. this gives you the value of the interquartile range.

false

using a very large sample is an effective way to reduce the errors created by a bias in sampling. is this true or false?

99.7%

if you go out 3 standard deviation units on both sides of the mean in a normal distribution, what percentage of the cases will be captured?

equal

in a scattergram the two axes lengths are

experiment

in order to determine cause and effect, a controlled experiment is needed

variation

If S equals 0 then there is no

7

What is the range of these scores:6,8,8,10,12,13

above the mean

a positive z-score indicates that a person is

properties of a Pearson r

• it can range only from -1.00 to 1.00 • -1.00 indicates a perfect negative relationship- the strongest possible inverse relationship • 1.00 indicates a perfect positive relationship-the strongest possible direct relationship • 0.00 indicates a complete absence of relationship • the closer a value is to 0.00, the weaker the relationship • the closer a value is to -1.00 to 1.00 the stronger the relationship

68%

____ of the cases lie within one standard deviation unit in a normal curve

below the mean

a negative z-score indicates that a person is

50%

a person with a z-score of 0.00 has a score that is higher than what percentage of the group in a normal distribution?

84%

a person with a z-score of 1.00 has a score that is higher than what percentage of the group in a normal distribution?

very strong

a positive scattergram is

one-tailed probability

a question asked only about the upper tail of the normal distribution- the right side

range

a simple statistic that describes variability

extremely weak relationship

a value of r=-.01 represents an

almost perfect relationship

a value of r=-.99 represents an

68%

if the mean for a group equals 27 and the standard deviation equals 3.00, what percentage of cases in a normal distribution lies between 24 and 30?

34%

if the mean for a group equals 40.00 and the standard deviation equals 5.00, what percentage of the cases in a normal distribution lies between 40 and 45?

no relationship

if there is no pattern it is said to be

no

if two groups are equal on average, will they necessarily be equal in their variability?

68%

if you go out 1 standard deviation unit on both sides of the mean in a normal distribution, what percentage of the cases will be captured?

what is a better measurement of variability?

interquartile range

r2

is r or r2 a more direct indicator of variance accounted for

interquartile range

is the range or interquartile range a better measure of variability?

Spread and dispersion

other names for variability

inverse relationship

pattern is from upper left to lower right

volunteerism

people who participate and refuse to participate

intersect

place 1 dot where the two scores for each individual intersects

sampling errors

random errors

sampling errors

random or chance errors

statistacally significant

rejecting the null hypothesis is declaring a result to be

type 1 error

rejecting the null hypothesis when it is true

directional hypothesis

research hypothesis that indicates the direction of the difference

non directional hypothesis

researcher believes there is a difference between scores but there is insufficient information to hypothesize as to which groups achievement is higher

variability

the differences among scores (how much they vary from each other)

curvilinear relationship

the dots form a curve that, starting from the left, goes up for awhile then turns downward

linear relationship

the dots form a pattern that follows a single straight line.

correlation

the extent to which two sets of scores are related.

standard deviation

the larger the deviations from the mean, the larger the

norm-reference interpretation

the norms for normal, below average, and above average, based on what has been commonly observed among large numbers of patients, provide reference points for interpreting raw scores.

raw scores

the number of points earned

alpha level

the probability at which researchers are willing to reject the null hypothesis

standard deviation

this is a measure of how much scores differ from the mean of the scores.

direct relationship (positive)

those who score high on one variable tend to score high on the other

inverse or negative relationship

those who score high on one variable tend to score low on the other

4.41

to two decimal places what is the standard deviation of these scores: 0,2,5,9?

1.72

to two decimal places, what is the standard deviation of these scores: 3,5,6,7,8?

97.50%

to two decimal places, what percentage of the cases in a norm distribution lie below a z-score of 1.96?

84.13%

to two decimal places, what percentage of the cases in a normal distribution lie above a z-score of -1.00?

68.26%

to two decimal places, what percentage of the cases in a normal distribution lie between a z-score of 1.00 and a z-score of -1.00?

95.00%

to two decimal places, what percentage of the cases in a normal distribution lie between a z-score of 1.96 and a z-score of -1.96?

coefficient of determination

useful when interpreting a Pearson r

3.00

what is the highest value in the effective range of z-scores?

3

what is the multiplier for the 99.7% rule?

2

what is the multiplier for the approximate 95% rule?

null hypothesis

what is the name of the hypothesis that says "the true difference between the means equals zero?"

2

what is the outlier in this set of scores: 2,18,18,20,20,21,22

0.0885

what is the probability of drawing a subject with a z-score of 1.35 or higher at random from a normal distribution?

0.0025

what is the probability that 2 and 8 will be drawn in a given lottery in which there are 20 numbers in play on each draw?

r2

what is the symbol for coefficient of determination

x

what is the symbol for the deviation of a score from its mean?

50%

what percentage of participants is encompassed by the interquartile range?

raw score

what term is used to refer to the number of points earned by an individual?

0

when all the scores are the same, the standard deviation equals

variability

when the median is reported as the average for a set of scores, it is customary to report the interquartile range as a measure of

positive relationship

when the pattern goes from the lower left corner to the lower right in a scattergram

many

when working with hundreds of participants, should an investigator expect many or few exceptions to an overall trend?

two-tailed probability

when you ask about the odds of drawing an individual at either tail of the normal distribution

bias

whenever some members of a population have a greater chance of being selected for inclusion in the sample than others

-2.52

if M=511.12 and S=20.28 and Sarah has a raw score of 460, what is the value of her z-score?

-1.00

if M=95 and S=5 and Jake has a raw score of 90, what is the value of his z-score?

0.0769

if a deck of 52 cards is shuffled, what is a probability, expressed as a proportion, that any of the for aces will be drawn?

above

if a person has a z-score of 1.50, is that persons score above or below the mean of the group?

.06

if r=.24, what is the value for r2

no

if r=.66, is the majority of the variance on one variable accounted for by the variance on the other?

77%

if r=.88, what percentage of the variance on one variable is accounted for by the variance on the other?

10%

if r=.95, what percentage of the variance on one variable is not accounted for by the variance on the other?

0.00

if something is certain not to occur the probability of non occurrence is ____

2

how many scores for each individual are required for a scattergram to be drawn?

1.00

if something is certain to occur, the probability of its occurrence is ____

standard scores

help interpret raw scores by indicating where an individual stands in a group.

.001 level

highly significant- reject the null hypothesis with even more confidence

what a standard score indicates

how many standard deviation units a person's score is from the mean and whether his score is above or below the mean

true

adding individuals produces diminishing returns in terms of reducing sampling errors. true or false?

population b

assume that population A has very little variability and that population B has much variability. for which population would a larger sample be needed for precise results to be achieved?

0.92

if M=42.35 and S=2.87 and June has a raw score of 45, what is the value of her z-score?

no

can a researcher be certain that there are no sampling errors if he or she uses random sampling?

variance

differences among the scores

null hypothesis

differences between the two scores due only to errors created by random sampling

simple random sampling

each member of a population is given an equal.chance to be selected

false

establishing a correlation establishes a causal relationship-true or false?

type 2 error

failing to reject the null hypothesis when, in reality, it is false

95%

for M=100.00 and SD=10.00, approximately what percentage of the cases lie between 80.00 and 120.00?

41-69

for M=55 and SD=7, between what two values do approximately 95% of the cases lie in a normal distribution?

45-135

for M=90 and SD=15, between which two values do approximately 99.7% of the cases lie in a normal distribution?

0.0668

for a normal distribution with a means of 100.00 and a standard deviation of 16, what is the one tailed probability of drawing a subject with a score of 124 or greater at random from a normal distribution?

6

for all practical purposes, the normal curve has how many standard deviation units?

false

for an r of .55, 55% of the variance on one variable is accounted for by the variance on the other. true or false?

99.7% rule

going up and down three standard deviation units from the mean identifies where 99.7% of the cases lie.

figure

label the scattergram as a ____ and give it a number and a brief title

.01 level

more significant- reject the null hypothesis with more confidence

where raw scores come from

multiple-choice tests, instruments that measure blood pressure, point systems for creativity in an artistic endeavor, essay examinations, etc...

.06+ level

not significant-do not reject null hypothesis

scattergram

scatter diagram and scatterplot are also names for a

outliers

scores that lie outside of the range of the vast majority of the scores and can greatly increase the size of the range

.05 level

significant- reject the null hypothesis

mean

standard deviation is also reported with the

z-scores

standard scores are also called

Pearson r

statistic for describing the relationship between two sets of scores

How do you find range?

subtract the lowest score from the highest score

parameters

summarized result of a population

statistics

summarized result of a sample

parameters

suppose a population of first grade teachers in a school district way surveyed on their attitudes toward a curriculum change, and all of the teachers in a population participated. the percentages were computed. are the percentages statistics or parameters?

p

symbol for probability

median

the IQ range is associated with which average?


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