Stats
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