IDS 270 Exam #1 – Actual Exam Content with
A+ Graded, Step-by-Step Solutions
How do you calculate the average? - ✔✔add all values up, divide by total number of values
Average is the same thing as... - ✔✔Mean
Observational study - ✔✔We observed the behavior or ask people questions as they're going about
their day-to-day lives. Ex: call people and ask them how often they eat out.
Experiment - ✔✔We impose some treatment on people and then observe their behavior or ask
questions. Ex: give people a drug and then do chemical analysis of their blood.
Confounded variables - ✔✔Two variables where the effect of one on the dependent variable cannot be
separated from the effect of the other. Ex: if you take drugs and drink alcohol, and then have a car
accident, the effect of the drug versus the alcohol cannot be separated from each other as the cause of
the accident
Population - ✔✔The set of everything. Ex: all the people in America
Sample - ✔✔A small group pulled from the population. Ex: sample 40 voters from the population of
America
Sample distribution - ✔✔The set of number within one sample
Voluntary response sampling - ✔✔People volunteer to give data for a study. Ex: people text a phone
number if they agree with a statement and text a different one if they disagree
Convenience sampling - ✔✔People are selected to be in a sample because of convenience or low
expense. Ex: mall intercepts, or asking the people on the floor of your dorm to fill out a survey
, Bias - ✔✔Systematically favoring a certain outcome from research
Simple random sampling - ✔✔Label all the people in the population with a number. Have a computer
select a set of random numbers in that range. People labeled with the number are selected for the
sample. Therefore, every person or sub-group of people has an equal chance of being in the sample.
Stratified sampling - ✔✔First breaking the population into natural segments (called strata) and then
using random sampling within the strata. Ex: radio stations or types of colleges (community colleges,
public universities, private universities, standalone liberal art colleges).
Multi-stage sampling - ✔✔Basically practicing stratified sampling repeatedly to get a final sample
Undercoverage - ✔✔Where some members of the population cannot be selected for the sample. Ex:
people without phones if one is collecting data over the phone
Non response - ✔✔When an individual selected for the sample does not provide information
Response bias - ✔✔Not answering truthfully when asked questions about sensitive subjects. Ex: "how
much pot do you smoke?"
Subjects - ✔✔People who are involved in an experiment
Factors - ✔✔The explanatory variables in an experiment
Level - ✔✔the specific values that the experimenter chooses for a factor
Treatment - ✔✔A unique combination of levels of factors given to a set of subjects
A+ Graded, Step-by-Step Solutions
How do you calculate the average? - ✔✔add all values up, divide by total number of values
Average is the same thing as... - ✔✔Mean
Observational study - ✔✔We observed the behavior or ask people questions as they're going about
their day-to-day lives. Ex: call people and ask them how often they eat out.
Experiment - ✔✔We impose some treatment on people and then observe their behavior or ask
questions. Ex: give people a drug and then do chemical analysis of their blood.
Confounded variables - ✔✔Two variables where the effect of one on the dependent variable cannot be
separated from the effect of the other. Ex: if you take drugs and drink alcohol, and then have a car
accident, the effect of the drug versus the alcohol cannot be separated from each other as the cause of
the accident
Population - ✔✔The set of everything. Ex: all the people in America
Sample - ✔✔A small group pulled from the population. Ex: sample 40 voters from the population of
America
Sample distribution - ✔✔The set of number within one sample
Voluntary response sampling - ✔✔People volunteer to give data for a study. Ex: people text a phone
number if they agree with a statement and text a different one if they disagree
Convenience sampling - ✔✔People are selected to be in a sample because of convenience or low
expense. Ex: mall intercepts, or asking the people on the floor of your dorm to fill out a survey
, Bias - ✔✔Systematically favoring a certain outcome from research
Simple random sampling - ✔✔Label all the people in the population with a number. Have a computer
select a set of random numbers in that range. People labeled with the number are selected for the
sample. Therefore, every person or sub-group of people has an equal chance of being in the sample.
Stratified sampling - ✔✔First breaking the population into natural segments (called strata) and then
using random sampling within the strata. Ex: radio stations or types of colleges (community colleges,
public universities, private universities, standalone liberal art colleges).
Multi-stage sampling - ✔✔Basically practicing stratified sampling repeatedly to get a final sample
Undercoverage - ✔✔Where some members of the population cannot be selected for the sample. Ex:
people without phones if one is collecting data over the phone
Non response - ✔✔When an individual selected for the sample does not provide information
Response bias - ✔✔Not answering truthfully when asked questions about sensitive subjects. Ex: "how
much pot do you smoke?"
Subjects - ✔✔People who are involved in an experiment
Factors - ✔✔The explanatory variables in an experiment
Level - ✔✔the specific values that the experimenter chooses for a factor
Treatment - ✔✔A unique combination of levels of factors given to a set of subjects
