statistics exam 1

Question 1

the basic unit of an experiment upon which the treatment is applied.

Answer 1

individual

Question 2

An experimental condition where neither the subjects nor the diagnosticians (doctor, nurse, etc) know which treatment each subject received.

Answer 2

double blind

Question 3

a weakness in experiments where the setting of the experiment does not realistically duplicate the conditions we really want to study.

Answer 3

lack of realism

Question 4

an experimental design where all individuals are assigned at random to treatments

Answer 4

completely randomized

Question 5

a study in which treatments are imposed on the individuals before responses are measured.

Answer 5

experiment

Question 6

the grouping of individuals according to some similar characteristics. The random allocation is carried out separately within each group.

Answer 6

Blocking

Question 7

A treatment where either no experimental condition or a placebo treatment is applied to the individuals in order to determine whether the active treatment works. This together with randomization enables the researcher to “control” lurking variables.

Answer 7

control

Question 8

A study in which data are gathered without imposing treatments on the individuals.

Answer 8

observational study

Question 9

A variable that is studied to determine whether it affects the outcomes of a study.

Answer 9

explanatory variable

Question 10

A variable that has an effect on the response variable but is not included as one of the variables in a study.

Answer 10

lurking variable

Question 11

the response of patients to any treatment that has no physical effect.

Answer 11

placebo effect

Question 12

a method of assigning individuals to treatment groups that eliminates bias and gives each unit the same probability of being assigned to any treatment group.

Answer 12

randomization

Question 13

results of a study that differ too much from what we expected because of randomization to attribute to chance.

Answer 13

statistically significant

Question 14

a situation where the effect of one variable on the response variable cannot be separated from the effect of another variable on the response variable.

Answer 14

confounding

Question 15

The application all the treatment combinations to more than one individual within an experiment

Answer 15

replication

Question 16

Type of sampling required for inference.

Answer 16

sample selected with some type of random device

Question 17

Using results from a sample to draw conclusions about the entire population.

Answer 17

inference

Question 18

A sampling scheme where the population has been divided into strata according to some characteristic and a simple random sample is selected from each stratum.

Answer 18

stratified sample

Question 19

A sample selected in such a way that the probability of each possible sample of size n has a known chance of being selected.

Answer 19

probability sample

Question 20

A method of sample selection that consists of people choosing themselves by responding to a general appeal.

Answer 20

voluntary response sample

Question 21

A condition that occurs when the design of a study systematically favors certain outcomes.

Answer 21

bias

Question 22

The entire group of individuals about whom we desire to collect information.

Answer 22

population of interest

Question 23

A subgroup of the population that we actually examine and about whom we gather information

Answer 23

sample

Question 24

A sample of size n selected from the population in such a way that every possible sample of size n has an equally likely chance of being selected.

Answer 24

simple random sample

Question 25

A sample type where the researcher contacts those subjects who are readily available and does not use any random selection.

Answer 25

convenience sample

Question 26

An observation that falls outside the overall pattern of the data set.

Answer 26

outlier

Question 27

measure for the center of the data that "balances" the data.

Answer 27

mean

Question 28

a measure of the center of data that splits the ordered data in half.

Answer 28

median

Question 29

A location measure of the data that has approximately one fourth or 25% of the data below it.

Answer 29

Q1

Question 30

A location measure of the data that has approximately one fourth or 25% of the data above it.

Answer 30

Q3

Question 31

s

Answer 31

sample standard deviation

Question 32

r

Answer 32

correlation coefficient

Question 33

n

Answer 33

sample size

Question 34

A representative measure of the deviations of the data about the mean

Answer 34

standard deviation

Question 35

maximum observation minus the minimum observation

Answer 35

range

Question 36

A measure of the "average" or typical deviation of the observations about the mean.

Answer 36

standard deviation

Question 37

The difference between the third quartile and the first quartile.

Answer 37

IQR, interquartile range

Question 38

the measure of variability that should be used for strongly skewed data or data with outliers.

Answer 38

interquartile range

Question 39

A curve that is mound shaped symmetric used to model data from measurements on animal species.

Answer 39

Normal Distribution

Question 40

A normal distribution that has a mean of zero and a standard deviation of one.

Answer 40

standard normal distribution

Question 41

A measure of the number of standard deviations of a value or observation from the mean.

Answer 41

z-score

Question 42

In a normal distribution, the percentages of values that are within on e standard deviation of the mean.

Answer 42

68%

Question 43

In a normal distribution, the percentage of values that are within two standard deviations of the mean.

Answer 43

95%

Question 44

A graph for categorical data

Answer 44

bar graph

Question 45

A plot of data that incorporates the maximum observation, the minimum observation, the first quartile, the second quartile, and the third quartile.

Answer 45

boxplot

Question 46

A distribution where the left side of the distribution extends in a long tail.

Answer 46

left skewed

Question 47

A list of the possible values of a variable together with the frequencies of each value.

Answer 47

distribution

Question 48

The shape of a distribution where the mean exceeds the median.

Answer 48

right skewed

Question 49

A plot used to provide a picture of one variable quantitative data.

Answer 49

stemplot, dotplot, histogram, or boxplot

Question 50

The shape of a histogram where the median exceeds the mean.

Answer 50

left-skewed

Question 51

The shape of a histogram where the mean equals the median.

Answer 51

symmetric

Question 52

The recommended plot for displaying small quantitative data sets

Answer 52

stemplot

Question 53

The preferred measures of spread and center for strongly skewed distributions or distributions with outliers.

Answer 53

median and interquartile range