2017-11-07 02 Exam Flashcards
Normal distribution and skewness
(Manual, 35)
- A skewness between -2 and +2 is normal
scales of measurement
(in-class 9/4) (A &; L, 79-83)
- nominal
- ratio
- interval
- ordinal (not needed)
nominal scale
(in-class 9/4) (A & L, 80) -used to measure categories
ratio scale
(in-class 9/4) (A & L, 80)
- true zero (fixed-point)
- used to measure quantities
interval scale
(in-class 9/4) (A & L, 80)
- used to measure ratings
- identity (each number has a specific meaning), order (numbers on a scale, in ordered sequence), equal intervals (distance between numbers on the scale is equal)
operational definition
(in-class 9/4) (A & L, 77)
- specifics of how the variable is measured
- so it can be exactly replicated
central tendency
(A & L, 147)
- central score
- summarizes center of distribution
- mode, median, mean
mode
(A & L, 149)
measures central tendency
- most frequent score in a distribution
median
(A & L, 149)
measures central tendency
- halfway point of distribution
mean
(A & L, 149)
measures central tendency
- arithmetic average
variability
(A & L, 150)
- how much scores are different from each other in a sample
- observed minimum, observed maximum, range, standard deviation
observed minimum
(A & L, 150)
measures variability
- lowest score in the sample
observed maximum
(A & L, 150)
measures variability
- highest score in the sample
range
(A & L, 150)
measures variability
- distance between observed minimum and maximum
standard deviation
(A & L, 150)
measures variability
- how much in general the scores in a sample differ from the mean
descriptive statistics
(A & L, 142)
- used to analyze quantitative and qualitative data
- quantitative analysis used to summarize characteristics of a sample
- CT: mode, median, mean
- Variability observed minimum, observed maximum, range, standard deviation
descriptive statistics for nominal data
(A & L, 170)
- frequencies and/or percentages
- CT: (sometimes mode)
- variability: –
descriptive statistics for interval or ratio (normal distribution)
(A & L, 170)
- (sometimes: percentages for each score on an interval scale)
- CT: mean
- variability: standard deviation (sometimes: possible min/max for interval, observed min/max for interval and ratio)
descriptive statistics for interval or ratio (skewed)
(A &; L, 170)
- (sometimes: cumulative percentage)
- CT: median
- variability: observed min/max or range
sampling
(A & L, 119)
- process of how the sample is selected
probability sampling (random sampling)
(A & L, 121)
- sampling procedure that uses random selection
- ideal, (external validity/generalizable)
- simple random, stratified random, cluster sampling
non-probability sampling (non-random sampling)
(A & L, 123)
- sampling procedure that doesn’t use random selection
- less time (no need to identify all participants [members, clusters] in a population)
- if researcher can’t identify all members/clusters, appropriate sample size, and/or minimize non-response data
- convenience, quota, maximum stratification, snowball,
convenience sampling
(A & L, 129)
non-probability sampling
- sample is volunteers who are readily available and willing to participate
- typically have an over-represented group
- easiest (feasable)
snowball sampling
(A & L, 132)
non-probability sampling
- participants recruit others into the sample
independent variable (and levels)
(A & L, 21) (in-class 8/29)
- variable that’s manipulated in an experiment
- Levels: a control group and then 1 or more other assignments/groups
dependent variables
(A & L, ) (in-class 8/29)
- variable that’s measured in an experiment
- expected to change based on IV
pilot study definition
(in-prac 9/18)
- still with target population
- test before spending money
- work on any possible changes
Pilot studies can find problems with
(in-class 10/24)
- recruitment
- retention (who will stay?)
- implementation (measures good?)
- assessment (is it accurate?)
- new methods (money)
Experimental design
(A & L, 19) 1 - random assignment 2 - IV manipulated (at least 2 levels) 3 - DV measured Main benefit: can determine causality
Random assignment definition
(A & L, 280, 184)
- essential for an experiment
- participants (already selected) chosen at random to IV conditions/levels
Random assignment and purpose
(A & L, 280, 284)
- increases internal validity
- IV groups to be as similar as possible before IV exposure
- evens out individual differences across IV conditions
(in-class 10/26)
- any group differences between groups isn’t the confounds (confounds affect both groups)
Independent variable (and levels)
(A & L, 21) (in-class 8/29)
- variable that’s manipulated in an experiment
- Levels: a control group and then 1 or more other assignments/groups
IV manipulation: reliable and valid
(A & L, 308)
- need equivalent IV levels/conditions
- manipulation check
Manipulation checks
(A & L, 292)
- Checking if what you manipulated what you wanted to manipulate
EX: if part of the study was to read a book, quiz participants on their comprehension of the book
Pilot studies can find problems with
(in-class 10/24)
- recruitment
- retention (who will stay?)
- implementation (measures good?)
- assessment (is it accurate?)
- new methods (money)
Confounding variables definition
(In-class 10/24) - History effect - Maturation effect - Testing effect - Instrumentation effect - Regression to the mean (statistical regression) (( usually more than one at once ))
Confounding variables: ways to limit
(In-class 10/24)
- random assignment
- manipulate ONE variable
- need equivalent IV levels/conditions
- large sample size