Measurement and Sampling Flashcards
what are variables?
something that varies
what does “constant” mean?
something that is fixed/does not change
what is a quantitative measurement?
the use of number to describe a property of an object or event
what is measurement?
the use of number to describe something that happens (or doesn’t happen) in the world
what are examples of measured things?
lecture attendance
temperature
clicks on a website
product units sold
brand reputation perceptions
what are examples of measurement acts?
taking a baby’s temp.
asking question on a survey
counting the number of likes on a tweet
what are the four levels of variable measurement?
(NOIR) nominal, ordinal, interval, ratio
what are the characteristics for nominal (or “categorical”) variables?
- numbers serve as tags or labels
- numbers are not placed on a meaningful scale
- higher/lower number doesn’t mean anything
- membership is both all inclusive and mutually exclusive
what are nominal variables with only two levels called?
dichotomous or binary nominal variable
T or F: This is an example of a nominal variable
Biological sex [1=male, 0=female]
True
What are the characteristics of ordinal variables?
- possible values are meaningfully ordered
- variables do not establish the numeric difference between data points
- indicate that only one data point is ranked higher or lower than another
- distance between number is not set or consistent
T or F: this is an example of ordinal variables
rate teacher effectiveness as excellent (5), good (4), average (3), poor (2) or unsatisfactory (1)
True
what are characteristics of interval variables?
- measured along a scale
- each position is equidistant from other scale points
how is an interval level of measurement achieved?
- if the categories of a variable can be ranked-order
- if the measurements for all the cases are expressed in the same units
T or F: This is an example of interval variables
GPA Scores: a 3.0 is exactly 0.5 GPA points below a 3.5
True
what is a ratio variable?
interval variables with a natural zero point
what does natural zero point mean?
the zero means “none of something”
T or F: this is an example of an interval variable
Distance: two things can be zero inches apart
True
True or False: Nominal attributes are only named, and are the weakest variable
True
T or F: Ordinal attributes can be ordered
True
T or F: interval distances are meaningful
True
T or F: ratio variables contain an absolute zero
True
What is a measurement error?
when the data we collected does not represent reality
T or F: measurement error isn’t always present
False: measurement error is always present to some degree
What are random measurement errors?
measurement errors that are small, non-systematic, and do not threaten the overall validity of data
What are systematic measurement errors?
an error in measurement in which the tool does not accurately measure the concept and is perceived incorrectly by most or all of the participants
What is reliability?
the consistency in our measurement
T or F: reliability refers to the level of clarity in the tool
True
What is validity?
the ability or potential of a data collection tool to capture and measure the construct or the phenomenon that we are interested in measuring
How is reliability different from validity?
reliability pertains to a measurement approach’s ability to yield consistent results
How is validity different from reliability?
validity refers to a measurement approach’s ability to measure what is supposed to happen
what is a population?
the entire group of people that are the focus of the study
what is a sample?
a subset of the population, ideally representative of all the characteristics of the population
Why do we sample?
it’s often impossible or counterproductive to collect data from all members of population
What are the different types of sampling approaches?
probability samples and non-probability samples
what are probability samples?
- every element of the population has a known chance of being selected for inclusion
- every element has a non-zero chance of being included in the sample
T or F: probability samples provide every element of the population with an equal change for inclusion
False
What are non-probability samples?
not all elements of a population have an opportunity to be included in the sample
T or F: probability samples do not allow us to make inferences about a population
False: non-probability samples do not allow us to make inferences about a population
what is inference?
a conclusion or opinion that is formed because of known facts or evidence
what are the different types of probability sampling?
1) simple random sampling
2) stratified random sampling
3) disproportionate random sampling
4) convenience sampling
5) snowball sampling
6) purposive sampling
7) quota sampling
what is simple random sampling?
all members of a population have an equal change of being selected for the sample
T or F: In simple random sampling, members of a population are selected at random for inclusion in the sample
True
What is stratified random sampling?
a population is divided into subgroups or strata, then a random sample is subsequently drawn from each strata
what is disproportionate random sampling?
similar to proportional random sample except that sample proportions are not equivalent to population proportions
what is convenience sampling?
sample is drawn from those that are available or easy to collect data from
what is snowball sampling?
generates a convenience sample of respondents then asks them to recommend others who might be interested in providing data
what is purposive sampling?
when researches purposefully select from a group of people of theoretical interest
- experts, extreme cases, typical cases
what is quota sampling?
generation of a sample that has attributes proportional to a given population
Are convenience samples okay?
Yes and No: they restrict the ability to make population-level inferences BUT are time and cost efficient
T or F: Convenience samples are created equally
False: they are not ALL created equally
