Statistics Exam 1

Front 1

a graphical representation of categorical data. Names of each category are listed on the x-axis and a bar is placed over each category name having height equal to the frequency (or percentage) in that category.

Back 1

bar graph

Front 2

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

Back 2

bias

Front 3

the grouping of individuals according to some characteristic like rats in the same litter or plots of land at the same location. the random allocation is carried out separately within each group.

Back 3

blocking

Front 4

a plot of data based on the five number summary. a line is drawn from the minimum observation to Q1; a box is drawn from Q1 to Q3 with a vertical line at the median and a line is drawn from Q3 to the maximum observation.

Back 4

boxplot

Front 5

a variable that can be classified into groups or categories such as gender, religion, zip-code, etc. typically, words are used to describe an individual.

Back 5

categorical variable

Front 6

a study where the explanatory variable has two active treatments rather than an active treatment versus a control. purpose of study is to determine which treatment works best rather than whether a treatment works. randomization together with comparison enables the researcher to control lurking variables and apply the laws of probability for inference.

Back 6

comparative study

Front 7

an experimental design where all individuals participating in the experiment are assigned at random to the treatments.

Back 7

completely randomized design

Front 8

a variable whose effect on the response variable cannot be separated from the effect of another variable on the response variable.

Back 8

confounded variable

Front 9

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

Back 9

confounding

Front 10

an 'inactive' treatment where no experimental condition is applied to the individuals in order to determine whether the active treatment works. randomizing together with a control enables the researcher to manage lurking variables when there is not a comparison group. this is not necessary for a valid experiment as long as two or more comparison treatments are used.

Back 10

control

Front 11

a sample where the researcher contacts those subjects who are readily available and does not use any random selection. the results are almost surely biased.

Back 11

convenience sample

Front 12

a list or a graph that shows the possible values of a variable together with the frequency of each value.

Back 12

distribution

Front 13

a one dimensional plot of a quantitative data set where each value in the data set is represented by a dot above its corresponding location on the x axis.

Back 13

dotplot

Front 14

neither the subject nor the doctor, nurse, or whomever is diagnosing the results knows which treatment the subject received.

Back 14

double blind

Front 15

a study where a treatment is deliberately imposed on each individual in the study before responses are measured in order to observe responses to the treatment. MUST have 1)control or comparison 2)randomization or 3)replication.

Back 15

experiment

Front 16

a variable that may or may not explain the outcomes of a study.

Back 16

explanatory variable

Front 17

another term for explanatory variable.

Back 17

factor

Front 18

plot the data

Back 18

first rule of data analysis

Front 19

minimum, Q1, median, Q3, maximum; preferred when data are very skewed or have outliers

Back 19

five number summary

Front 20

a graphical display of a quantitative data set; data are separated into intervals of equal width and a bar is drawn over the interval having height equal to the frequency (or percentage) of values in the interval.

Back 20

histogram

Front 21

the basic unit (or subject) of the experiment upon which a treatment is applied.

Back 21

individual

Front 22

a measure of variability recommended for skewed data or data with outliers; computed Q3-Q1

Back 22

interquartile range (IQR)

Front 23

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

Back 23

lack of realism

Front 24

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

Back 24

left skewed

Front 25

a variable that has an important effect on the relationship among the variables in a study but is not taken into account

Back 25

lurking variable

Front 26

a measure for the center of the data; it's the point that balances the data

Back 26

mean

Front 27

a measure of the center of data; it's the point such that half the numbers are smaller and the other half are larger (the midpoint of the ordered data set)

Back 27

median

Front 28

sampling is conducted in stages; for a two stage sample, the individuals are grouped according to some characteristic-groups are first randomly selected and then individuals are randomly selected from those selected groups.

Back 28

multi-stage sample

Front 29

bias resulting when individuals selected to be in a survey either cannot be contacted or refuse to answer survey questions

Back 29

non-response bias

Front 30

a bell-shaped symmetric density curve used to model many data sets that have a symmetric mound or bell shape

Back 30

normal distribution

Front 31

a study that merely observes conditions of individuals in a population and records information; the population is disturbed as little as possible.

Back 31

observational study

Front 32

an observation that falls outside the overall pattern of the data set

Back 32

outlier

Front 33

a graphical display of categorical data using a "pie"; each category is represented as a slice where the size of the slice is proportional to the percentage of data in that category. not recommended by statisticians.

Back 33

pie chart

Front 34

the response of patients to any treatment even though it has no physical effect.

Back 34

placebo effect

Front 35

the entire group of individuals about whom we desire to collect information

Back 35

population

Front 36

a sample selected using a random device where each individual in the population has a chance (doesn't have to be equal) of being selected. necessary for making inferences.

Back 36

probability sample

Front 37

a location measure of the data such that has one fourth or 25% of the data is smaller than it.

Back 37

Q1

Front 38

a location measure of the data that has three-fourths or 75% of the data is smaller than it.

Back 38

Q3

Front 39

a variable with numerical values such as height or weight. this is required for both variables in regression analysis.

Back 39

quantitative variable

Front 40

a table of digits consisting of digits 0 through 9 whose order cannot be determined but in the long run, each digit occurs 10% of the time.

Back 40

random number table

Front 41

a method of assigning individuals in an experiment to treatment groups using some random device that eliminates bias and gives each unit the same probability of being assigned to any treatment group.

Back 41

randomization

Front 42

the maximum observation minus the minimum observation. given as one number in statistics

Back 42

range

Front 43

having more than one individual in each treatment group. necessary for measuring variability.

Back 43

replication

Front 44

bias resulting from individuals in a sample lying or giving incorrect responses because they do not have knowledge about the question or can't recall.

Back 44

response bias

Front 45

a variable that gives the result (may not be a number) of the outcome of a study.

Back 45

response variable

Front 46

a density curve where the right side of the distribution extends in a long tail

Back 46

right skewed distribution

Front 47

a subset of individuals in the population; the group of individuals about which we actually collect information

Back 47

sample

Front 48

a sample of size n selected from the population in such a way that each possible sample of size n has an equal chance of being selected

Back 48

simple random sample

Front 49

a measure of the average or typical deviation of the observations about the mean; measures variability of data about the mean

Back 49

standard deviation

Front 50

a normal distribution with mean of zero and standard deviation of one. probabilities are given in table A for values of the standard Normal variable

Back 50

standard Normal curve

Front 51

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

Back 51

statistically significant

Front 52

a graphical representation of a quantitative data set. leading values of each data point are presented as stems and second digits are given as leaves

Back 52

stemplot

Front 53

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

Back 53

stratified sampling

Front 54

a density curve where the right half is a mirror image of the left half of the distribution

Back 54

symmetric distribution

Front 55

bias that occurs because the list of the population from which the sample is drawn is incomplete-meaning that some people in the population are not listed for selection

Back 55

undercoverage bias

Front 56

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

Back 56

voluntary response sample

Front 57

a measure of the number of standard deviations a value or observation is from the mean, a standardized value

Back 57

z-score