Exam 2 Quantitative Analysis Flashcards
Statistical Analysis
Purpose - findings that are significant, also clinically significant
Probability Sampling
What is it?
Sampling method in which elements in the accessible population have an equal chance of being selected for inclusion in the study
Probability Sampling
What is a biased sample?
Doesn’t look like the population ‘you’ are wanting to look at
Probability sampling
What is sampling error?
What ‘we’ got, vs the truth
Probability sampling
how does sample size affect statistics?
Larger the sample, better off to find relationships…if you’re looking for subtleties, need larger groups
Types of stats
Descriptive
describe sample, what sample looks like, basic relationships
Types of stats
inferential
helps make generalizations
Types of stats
Univariate
One variable (ex.age)
Types of stats
Bivariate
two variables
Types of stats
multivariate
> two variables
Types of stats
Two categories of inferential
Parametric
Nonparametric
Descriptive
Describing the sample
Descriptive
Frequency
Stem-and-leaf plots (hash marks)
histograms (Bar graph)
frequency polygons (line graph)
Central tendency
Mode
Most frequent score
Central tendency
Median
Middle score
Central tendency
Mean
Average score
Normal curve
Symmetrical. “Bell curve”
Normal curve is very rare when dealing with people…going to have outliers
Skewed curve
Asymmetrical
Tail is right sided…positive
tail is left sided…negative
Kurtosis
How tall or flat the curveis
Range
spread of scores
difference between highest and lowest score
Semiquartile or interquartile range
the range of the middle 50%…divide range into quarters, discard Q1 and Q4…gets rid of the outliers
Standard deviation
How far someone is away from the average
Bivariate correlations
Two groups
looking for RELATIONSHIP between two scores (similarities)
Direction of relationship - negative
X goes up, Y goes down
Direction of relationship - positive
X goes up, Y goes up
Magnitude or strength of relationship
Weak…score close to 0
Strong…score close to +1 or -1
Remember… -0.6 is stronger than +0.2
When use pearson r
if using interval or ratio
When use spearman rho?
If using ordinal
Scatter plots
If the dots form a PERFECT line, regardless of direction, then perfect correclation
If the dots are completely scattered no semblance of a line, then no correlation.
If dots are in the general form of a line, but not perfectly straight…that is typical correlation.
Inferential statistics
Making suppositions about the population from information you know about the sample