Final Flashcards
What is the “who”
Study units or simply who the subjects or participants are
Sample
representative sample of a target population
parameter
measure of a population
statistic
measure of a sample
explanatory or predictor variables
independent variables
response variable
dependent variable
extraneous variables
explanatory variables that are not of interest that could affect the response variable
systematic sampling
First-person is selected randomly
Then Every [period of time]
Then Every nth person
Stratified vs cluster
Stratified: Population is divided into groups based on prior information. Then within each group random sampling is done. Alberta example
Cluster: Randomly select groups of people and then all people within these groups are interviewed.
Voluntary response bias
Asking for volunteers but people who like something are more likely to volunteer
Response bias
Loaded questions: Questions suggest or prompt a particular response favored by the researcher
Nonresponse bias
Large amount of people fail to respond to questions
Difference between observational and experimental studies
In observational studies, there is no manipulation or control of variables/conditions. In experiments there is deliberate manipulation of explanatory variables
Observational studies population and casual inferences
Population inferences: Can be made with random selection
Casual Inferences: Can NOT be made as there is too many extraneous variables. cause and effect cannot be made
Experimental studies population and causal inferences
Both can be made if there is random selection and random assignment
Relative frequency
Frequency divided by total number of observations
Pie Chart
Frequency of categorical data
Bar Graph
show the frequencies for one variable
Marginal and joint distribution
Marginal: Total frequency for each variable
Joint: Frequency of joint event
Conditional distribution
Negative skew vs positive skew
Median and mean resistance
Median is resistant to extreme values or skewness
Mean: is NOT resistant because it is influenced by skewness
Skewed distribution best measure of centre and spread
Centre: Median
Spread: Quartiles
Symmetric distributions best measure of centre and spread
Centre: Mean
Spread: Standard deviation
Mean mode and median in right/positive skewed
Mode < Median < Mean
RODE
Mean mode ande median in left/negative skewed
Mean < Median < Mode
If there is an odd set of observations is the median included
no
Boxplots parts
Population standard deviation
Boxplots skew
Quartiles skew
Probability for at least one
Sample size for normal distribution
> 30
between a small sample and a large sample, when sampling is taken, which has more variability
smaller sample has more variability
Calculating quartiles
height calculation for a uniform distribution
The variance between two values