Chpt 1,2--Collecting, Summarizing, Organizing Data

Question 1

population

Answer 1

the entire group of individuals to be studied.

population > sample > individual

Question 2

individual

Answer 2

a person or object from which we want to collect data; that is in the population being studied.

population > sample > individual

Question 3

sample

Answer 3

a subset of the population being studied.

population > sample > individual

Question 4

statistic

Answer 4

a numerical summary of a sample.

(vs. a parameter, which is a numerical summary of a population)

Question 5

descriptive statistics

Answer 5

when you organize and summarize statistical (sample-based) data.

Question 6

parameter

Answer 6

a numerical summary of a population

(vs. a statistic, which is a numerical summary of a sample)

Question 7

convenience samples

Answer 7

sampling methods that are not reliable

Question 8

inferential statistics

Answer 8

extend results from a sample to a population.

Then, measure the reliability of the result to determine level of confidence.

Margin of error accounts for uncertainty.

Question 9

the statistical process

Answer 9

1. identify the research objective
2. collect the data
3. describe the data
4. perform inference

Question 10

qualitative variable

Answer 10

categorical; classification based on attribute or characteristic

Question 11

quantitative variable

Answer 11

numerical; can be added or subtracted to provide meaningful results. How much, how many, how often.

Two types of quantitative variables:
1. DISCRETE variables have a finite number of possible values; result from counting (likely integer values).
2. CONTINUOUS variable have infinite possible values; value is measured (rather than counted).

Question 12

variable

Answer 12

a variable is a characteristic of the individual being studied.

Question 13

data

Answer 13

specific values of the variables

Question 14

levels of measurement

Answer 14

(NOIR)
If the variable
…categorizes, then NOMINAL measurement.
…categorizes AND allows ranking, then ORDINAL.
…if difference in value has meaning, but zero does NOT = absence, then INTERVAL (ex. tempurature).
…if the difference in value has meaning AND zero starting point, then RATIO (ex. #days)

Question 15

observational study

Answer 15

measures value without attempting to influence either the explanatory or response variables.

Three types of observational studies:
1. cross-sectional studies = snapshot
2. case-control studies = retrospective
3. cohort studies = prospective over a long period of time.

Question 16

explanatory variable

Answer 16

independent variable
(can affect the value of a response variable)

Question 17

response variable

Answer 17

dependent variable
(can be affected by an explanatory variable)

Question 18

confounding vs. lurking variable

Answer 18

confounding variables are considered in a study, lurking variables are not.

Question 19

census

Answer 19

list of all individuals in a population along with certain characteristics of each individual.

Question 20

stratified sample

Answer 20

separate population into non-overlapping groups, then obtain simple random sample from each group.

Question 21

cluster sample

Answer 21

select ALL individuals within a randomly selected collection or group of individuals.

Question 22

systematic sample

Answer 22

select every kth individual from the population. (ex. surveying grocery store customers)

Question 23

sampling error

Answer 23

error resulting from sampling–from using a subset of the population to describe characteristics of the population. A result of incomplete information.

vs. NON-SAMPLING ERROR is error from other factors.

Question 24

sampling bias

Answer 24

the technique used to obtain the individuals for the sample tends to favor one part of the population over another.

Question 25

non-response bias

Answer 25

individuals selected to be in the sample who do NOT respond to the survey have different opinions than those that do.

Question 26

response bias

Answer 26

present when responses do not reflect the true feelings of the respondent.

Can be due to interviewer error, wording of questions, order of questions, etc.

Question 27

randomized block design experiment

Answer 27

an experimental design in which the experimental units are divided into homogeneous groups called blocks; within each block, the experimental units are randomly assigned to treatments

Question 28

matched-pair design experiment

Answer 28

an experimental design in which the experimental units are paired up based on some criteria

Question 29

completely randomized design experiment

Answer 29

an experimental design in which each experimental unit is randomly assigned to a treatment group

Question 30

class width

Answer 30

the difference between lower class limits

Question 31

class midpoint

Answer 31

sum of consecutive lower class limits, divided by 2.