Statistics III Flashcards
Descriptive Statistics
Describe how many observations were recorded and how frequently each score or category of observations occurred in the data
inferential statistics
makes predictions about a population based on a sample of data taken from the population in question
2 types of statistics
Descriptive
Inferential
Inferences are based on _____
probability
In statistics, what is considered ‘significant’ p values?
p
what are the Two types of Inferential Statistics?
Comparative statistics
Regression statistics
What are the two types of Hypothesis testing?
null hypothesis Ho
alternative hypothesis Ha
What is Ho?
negative statement or no difference b/w two means
What is Ha?
alternative hypothesis or there is a difference bw/ two means
4 types of variables?
Nominal/categorical
ordinal/ranked
interval/numeric
ratio
What is nominal/categorical data?
Data that have names or arbitrary numeric assignments, unordered categories
Yes, No. Race/ethnicity, gender
What is ordinal data?
Data that can be arranged in ascending or descending order
Highest level of education, survey questions (disagree>neutral>agree) income categories
What is interval data?
Data with no true zero
Temperature, percent change
What is ratio data?
Numbers on a scale with a meaningful zero.
Height, weight, cholesterol levels
Two types of variables in hypothesis testing
Independent vs. dependent
What is Independent variable?
Variable that is systematically manipulated by investigator to show the effect on the outcome of experiment
changing diet to show body weight outcome
What is the dependent variable?
Response that is measured as a result of the independent variable
Variable likely to be though of as a different by the researcher
________ is based on the probability of a chance
Significance
What are the basic properties of Probabilities?
Property 1: probability of an event occurring is always b/w 0 and 1(0%-100%)
Property 2: the probability of an event that cannot occur is 0 (i.e pigs flying)
Property 3: The probability of an event that must occur is 1 (ie. sun rising in the east)
p
reject the null hypothesis
p>α
fail to reject the null hypothesis
Test decisions with ___________
confidence intervals
The probability that a particular value lies within this interval is called a _________
level of confidence
Confidence intervals are used with 2 types of tests
Odds ratio OR
Rate Ratios RR
CI that does not overlap 1 is equivalent of a p value of ____
p<0.05
If CI overlaps 1, that is equivalent to a p value of ____
p>0.05
2 categories of a test
parametric
non-parametric tests
what is a parametric test?
assume that the variables have a particular distribution (normal distribution) to assess the p-value of the outcome
typically used for ratio and internal variables
What is a non-parametric test?
typically used for ranked variables, categorical variables or when the distribution is not normal (skewness)
What is a T-test?
useful statistical test that determines whether there is a difference b/w two means is significantly greater or lesser than would be expected based on the populations.
Can only assess one variable at at time!!!!
What is a Chi Square test?
measures the differences bw what is observed and what is expected according to an assumed hypothesis
T- Test analyses _____
continuous data
Chi-Square analyses _____
categorical data
What is correlation?
allows us to measure the relationship b/w two or more variables
Two types of correlation ests
pearson (parametric)
spearman (non-parametric)
r=_______
correlation coefficient
If the r is close to -1, then there is a _________
strong negative correlation
If the r is close to 0, then _________
there is no linear relationship
If the r is close to +1, then there
is a strong positive correlation
What is regression?
Test to see if we can predict an unknown variable’s value based on the value of a known variable or variables
If outcome is is continuous, then there is one independent variable with 2 group, use _____
t-test
If outcome is is continuous, then there is one independent variable with 3+ groups, use ____
ANOVA
If the outcome is continuous and there is more than one independent variable use ____ if all independent variables are categorical
ANOVA
If the outcome is continuous and there is more than one independent variable use ____ or multiple linear regression, if only some independent variables are continuous
ANCOVA (analysis of covariance)
One way ANOVA
used to compare the mean values of continuous variables among independent groups
Two way ANOVA
way of studying the effects of two factors separately and/or together
