W2: RQ for Associations (Page 1-22) Flashcards
What does a good research question contain:
- ) A question
- ) All constructs being investigated
- ) The study population
- ) A verb that indicates the type of relationship among constructs being proposed
What are the 3 types of verbal forms of relationships
Difference; Association; Prediction
What does DAP involve
Association = Correlation Prediction = Linear Regression Difference = Differences between groups
What is a population
COMPLETE set of all individuals relevant to our research question
What is a sample
SUBSET of individuals selected by some sampling scheme from the population, assumed to be representative of that population
How many population and samples are relevant in our research question
1 population but there can be (theoretically) many possible samples drawn from that population
What is a construct
Unobservable attributes to explain human behavior
What is a measure. What are some conditions for a measure?
Method to measure people on a construct to obtain a construct score.
Measure must be valid and reliability
What is a score
Numerical value of the construct measure
What is a raw score and what are they generally indicated by
Values obtained directly from the construct measure.
They are generally indicated by a capital letter (X,Y), which is a variable containing a set of values
What is a deviation score and what are they generally indicated by.
Hence
The mean is subtracted from the individual score.
They are generally indicated by lower case letter (x,y)
Hence, X - mean(x) = x
What is a z score. What is the mean and sd of z scores
Particular kind of standardized score by dividing a deviation score by standard deviation
Mean = 0
SD = 1
(always)
What is a standardized score (Generally speaking)
Raw scores that have been transformed such that they have a predefined mean and a predefined scaling for each unit standard deviation.
IQ: 100
Z: 15
Why do we call something a random variable
Each value has an associated probability of ocurrene
What is the difference between continuous and discrete random variables
Continuous: Any numerical value within a defined interval (e.g. 0 to 100)
Discrete: Finite number of distinct values (e.g. integers 1,2,3,4,5)
If both measures are continuous, we use ___
Correlation
If both measures are categorical, we use ____
Contingency Tables
What is summary characteristics
Some kind of aggregation undertaken on
the individual values in one or more variables to produce a single quantity that is
informative about the values (e.g. mean; standardd deviation)
PPSS
Population - Parameter; Sample - Statistics
What is population parameter and sample statistics
PP = Aggregated summary characteristic of individual scores derived from all members of a population
SS = Aggregated summary characteristic of individual scores calculated in a single sample drawn from a population (i.e. there can be many values for a sample statistic, one for each sample drawn from the same population)
Do sample distributions vary. What does this imply about the sample mean.
Yes. Sample mean, etc… will randomly differ
What is the benefit of scatter plot
Useful for indicating an association. Can be linear/non-linear
What is a Pearson Correlation
Measure of LINEAR SYMMETRIC association between 2 CONTINUOUS variables
How are associations between multiple variables often presented
Often a correlation matrix
What do we use to identify patterns among multiple variables
Correlation plots are preferable for identifying patterns among multiple variables
Is positive or negative in value important when discussing association strength
No. We ignore positive or negative
What is the population correlation coefficient
p (rho). Correlation calculated on everybody in a population
What is the sample correlation coefficient
r. estimated on a sample drawn from a population
Do we often know p (rho)?
Almost certainly unknown.
We use the known sample value to estimate the unknown population value (point of research)
What is a sampling distribution/distribution of values
A sample statistic obtained from a large number of repeated samples taken from a population
What are the effects of having a larger sample size
Larger sample reduces variability of the sampling distribution (i.e. more narrow)
What is the SD of the sampling distribution
Standard Error.
What can each sample statistic value be regarded as
An estimate of the population parameter value
What is a confidence interval. What does it have.
- Range of plausible values* of an unknown population parameter based on the (1) value of a single sample statistic and (2) its standard error.
- Lower bound and upper bound value. Typically set as 95%.
What is a random sample. How is it typically done
A Simple Random Sample is one where each member of the population has an EQUAL probability of being selected.
It is typically done via. a uniform probability distribution (without replacement)
When we transform a score into a standardized score, what actually changes
Only the scaling of the variable
When we transform item scores as continuous, what we declare them in R
Declare them as numeric variables
When we treat item scores as discrete, what we delcare them in R
Declare them as factor variable
If we measure everyone in the population on a construct, then the set of scores form a …
Population distribution (There is only one)
If we measure everyone in a single sample from a construct, then the set of scores form a …
Sample Distribution (There are many possible)
Will the population distribution be larger/smaller than a sample distribution
Much Larger
What does it mean by “symmetry” in a Pearson Correlation
Correlation of X and Y = Correlation of Y and X
What is the correlation value always between
-1 to +1
Will any kind of sample statistic have a corresponding sampling distribution. Elaborate
In Theory, yes.
- Anytime we have a distribution of values, we can calculate summary characteristics.
Under conditions, as Sampling increases,
- ) Mean of sampling distribution will get closer to unknown population parameter value
- ) SD can be calculated (known as Standard Error)
How many types of scores are there
- ) Raw Score
- ) Deviation Score
- ) Z-Score
- ) Standardised Score
Deviation, Z and Standardized Scores are transformations of Raw Score
What do the scores and the transformation actually change
Only the scaling of the variable are changed
