Stats

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Q1

25% of the data are less than or equal to this value.

Q2

50% of the data are less than or equal to this value.

Q3

75% of the data are less than or equal to this value.

placebo group

A control group of participants who believe they are receiving treatment, but who are only receiving a placebo.

line graph

A graph that uses line segments to show changes that occur over time

uniform graph

A graph where all the class have the same frequency.

pictograph

A picture or drawing representing words or ideas

meta-analytic study

A study that compiles information from previous studies

double-blind study

An experiment in which neither the participant nor the researcher knows whether the participant has received the treatment or the placebo

Categorize the following studies as either a meta-analysis or a case study. Meteorologists study the Indian Ocean tsunami of December 2004 to try to identify warning signs.

Case study

Identify the sampling technique used for the following study. Poll each member of the entire sampling frame.

Census

What is the sampling technique used here? For budget purposes, a college president needs to know the average length of tenure of faculty at their college.

Census

Identify the sampling technique used for the following study. A market researcher interviews each member from each of the fifteen randomly chosen voting districts in a county.

Cluster sampling

What is the sampling technique used here? A random number generator is used to choose twenty-five regions. Then a quality assurance analyst collects data from each person in these regions.

Cluster sampling

Which type of sampling is this? An educator chooses 55 of the school districts in the Chicago area and asks each household in those districts how many school-age children are in the home.

Cluster sampling

Which type of study is this? A gastroenterologist surveys 130 of his patients six months after having gastric bypass surgery to determine the average amount of weight lost.

Cross-sectional study

To perform a research study, you need to obtain approval from an...

Institutional review board

Which type of study is this? A group of 220 patients is followed for 15 years in order to determine the long-term health effects resulting from gastric bypass surgery.

Longitudinal study

Categorize the following studies as either a meta-analysis or a case study. Oceanographers study research on tsunamis dating from 1900 to 2000 to determine their effects on the ocean floor.

Meta-analysis

Determine whether an observational or experimental study is appropriate to address the following statement. A general manager of a restaurant wants to find out her average daily receipts.

Observational

discrete data

Quantitative data that can take on only particular values and are usually counts

Which type of sampling is this? To determine who will win a $100,000$⁢100,000 shopping spree at the mall, the manager draws a name out of a box of entries.

Random sampling

Identify the sampling technique used for the following study. A scientist chooses ten people at random from each neighborhood.

Stratified sampling

What is the sampling technique used here? First, the population is subdivided by metropolitan area. Then a quality assurance analyst uses a random number generator to select twenty-five members from each metropolitan area to study.

Stratified sampling

Which type of sampling is this? A pollster surveys 50 people in each of a senator's 12 voting precincts.

Stratified sampling

Which type of sampling is this? The quality control department at a cereal manufacturer measures the weight of every 10th box off of the assembly line.

Systematic sampling

interquartile range

The difference between the upper and lower quartiles.

Rounding rule

When calculating the percentile of a data value, round to the nearest whole number.

stratified sample definition

a few members of each group

Institutional Review Board ( IRB)

a group of people who review the design of a study to make sure that it is appropriate and that no unnecessary harm will come to the subjects involved.

relative frequency histogram

a histogram in which the heights of the bars represent the relative frequencies of each class rather than simply the frequencies

frequency polygon

a visual display created by plotting a point at the frequency of each class above each class midpoint and connecting the points using straight lines

single-blind experiment

an experiment in which the participants are unaware of which participants received the treatment, but the researcher knows

Processing errors

are errors that occur simply from the data being processed, such as typos when data are being entered

dropouts

are participants who begin a study but fail to complete it

nonadherents

are participants who remain in the study until the end but stray from the directions they were given

frequncies (f)

are the numbers of data values in the categories of a frequency distribution

cross-sectional study

characterized by data that are collected at a single point in time.

cluster sample

chose by dividing the population into groups called clusers that are each similar to the entire population

systematic sample

chosen by selection every n^th member of the population

qualitative data

consist of labels or descriptions of traits

Quantitative data

consists of counts or measurements

Which type of sampling is this? A female student walks down the halls in her dorm asking students how much money they would spend in a food court in the dorm lobby in an effort to persuade the administration to offer such an option.

convenience sample

longitudinal study

data are gathered by following a particular group over a period of time.

cross-sectional graph

displays information collected at only one point in time

dot plot

displays the data without grouping certain points together like the stem-and-leaf plot does. Instead, only data that are exactly the same appear together

Example of random sampling

drawing names from a hat

cluster sample definition

each member of a few groups

random sample

every member of the population has an equal chance of being selected

simple random sample

every sample from the population has an equal chance of being chosen

confounding variable

factors other than the treatment that cause an effect on the groups

bias

favoring of a certain outcome in a study

experiment

generates data to help identity cause and effect relationships

representative sample

has the same relevant characteristics as the population and does not favor one group from the population over another

indicates to take the sum of what follows

informed consent

involves completely disclosing to participants the goals and procedures involved in a study and obtaining their agreement to participate.

class

is a category of data in a frequency distribution

frequency distribution

is a display of the values that occur in a data set and how often each value, or range of values, occurs

time series graph

is a line graph that is used to display a variable whose values change over time

stem and leaf plot

is a quick way to depict the frequencies of the data without having to first create a frequency distribution

Distribution

is a way to describe the structure of a particular data set or population

class width

is the difference between the lower limits or upper limits of two consecutive classes of a frequency distribution

relative frequency

is the fraction or percentage of the data set that falls into a particular class

upper class limit

is the largest number that can belong to a particular class

cumulative frequency

is the sum of the frequencies of a given class and all previous classes. The cumulative frequency of the last class equals the sample size

Percentile formula

l=n⋅P100

Case study

looks at multiple variables that affect a single event

ordinal level of measurement

measurement of qualitative data that can be arranged in a meaningful order

interval level of measurement

measurement of quantitative data that can be arranged in a meaningful order, and the differences between data entries are meaningful

example of systematic sampling

measuring every 100th item that comes off an assembly line

stratified sample

members of the population are divided into two or more subgroups called strata, that share similar characteristics like age, gender, race

observational study

observes data that already exists

researcher bias

occurs when a researcher influences the results of a study

response bias

occurs when a researcher's behavior causes a participant to alter his or her response or when a participant gives an inaccurate response

sampling bias

occurs when the sample chosen does not accurately represent the population being studied

nonresponse bias

occurs when there is a lack of participation in a self-selected sample from certain segments of a population, when a person refuses to participate in a survey, or when a respondent omits questions when answering a survey

participation bias

occurs when there is a problem with the participation—or lack thereof—of those chosen for the study

convenience sample

one in which the sample is convenient to select

class midpoint

or class mark, of a class is the sum of the lower and upper limits of the class divided by 22. The midpoints are often used for estimating the average value in each class

Participants

people being studied in an experiment

subjects

people or things being studied in an experiment

nominal level of measurement

qualitative data consisting of labels or names

continuous data

quantitative data that can take on any value in a given interval an are usually measurements

ratio level of measurement

quantitative data that you can order & differences have meaning & there IS a natural zero

The three main principles in experimental design are to

randomize control replicate

lower class limit

s the smallest number that can belong to a particular class

Experiments

seek to create data to help identify cause-and-effect relationships.

Treatment

some condition that is applied to a group of subjects in an experiment

ogive

that depicts information from a frequency distribution. It shows the cumulative frequency of each class

sample mean

the arithmetic average value of the responses on a variable

symetrical graph

the data lie evenly on both sides of the distribution

control group

the group that does not receive the treatment.

Treatment group

the group that receives the treatment

weighted mean

the mean obtained by assigning each observation a weight that reflects its importance

population mean

the sum of the values in the population divided by the population size

skewed to the left

the tail to the left of the peak is longer than the tail to the right of the peak

skewed to the right

the tail to the right of the peak is longer than the tail to the left of the peak

class boundary

the value that lies halfway between the upper limit of one class and the lower limit of the next class

explanatory variable

the variable in an experiment that causes the change in the response variable

response variable

the variable in an experiment that responds to the treatments


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