Test 3: Regression Equations, Types of Measurement, Survey Design and Sampling. Flashcards
regression lines is an “____”
estimate. it is the predicted y value. Thus, there will always be some degree of error where the predicted y value may differ from the observed y value.
residual on a graph is determined by:
the distance upwards or downwards from the regression line to the observed data point.
Residuals can be….
(A) Large or Small
(B) Positive or Negative
(C) Null (perfect
prediction)
regression line as a line of ______. if placed correctly…
> best fit. > It should sit in the middle of all the data points. > If accurately placed then the residuals (error) should add to 0. i.e. all the positive and negative valued error should equate to 0.
What is the goal for a regression equation?
Provide the best estimate of how to predict the y-values (DV) from the x values (IV).
thus, to understand the correlation between two variables we need the slope of the regression/correlation line to identify the direction and strength of the association between x and y.
Moving the regression line along the y-axis or adjusting it’s tilt will….
create more misfit i.e. increase the residuals.
In a regression we are predicting __ not __
the DV not the IV!
How does Methods link to methodology?
How we decide to define, and measure constructs is a large part of the research process. What is equally as important is the ability to test is the measure is both reliable and valid.
What is the point of Measurement?
In science, we aim to make “good” measurements of psychological phenomena. What two core concepts within the philosophy of science does this relate to?
(A) Theory/Predictions
(B) Theoretical debates are filled with constructs, hypothetical psychological phenomena that cannot be measured directly.
Observations
Derived from data, observations are used to shed light on those constructs. This is done by using measurement to capture data that represent those constructs.
Representations of Constructs/Conceptual Variables are derived using?
operationalizations.
Example:
Wellbeing is a conceptual variable or construct that can be defines with words but cannot be directly measured- it’s intangible.
Thus, researchers need to operationalize this variable into terms that makes it both observable and measurable.
i.e. we can measure the construct indirectly, by measuring the representation of it we decide on through our operational definition.
To determine if two constructs are theoretically linked one must ….
a meaningful conclusion is contingent on?
compare the observable variables which represent the conceptual variables respectively. This is contingent on the two measures both being reliable and valid in order for a meaningful conclusion to be drawn.
“Good” Variables are both ___ why is this important?
reliable and valid. Why? This allows us to be confident that our proxy measure is representing the construct and not something else (i.e. another construct or error).
variables are ___ and _____?
Measurable representation of an abstract construct.
A proxy/indirect measure of said construct.
measurements are generally more reliable if… ___ or ___.
(A) Measures that don’t include a lot of “noise” (= error)
Most psychological measurements contain relatively high amounts of “random variation” (i.e. naturally occurring variation withing the data, error, that we aim to minimize) due to contextual factors.
For example, variation due to equipment, or physiological changes.
(B) Measures obtain focused information about the
core construct
For example, self-report scales need multiple items that represent the construct being measured.
Note: Noise, Random Variation, Error are the same thing.
Implications of physiological, observational data and Self-Report Measures, respectively:
Physiological Measures:
Needs to be repeatedly measures across multiple time points.
Data has to go through an extensive data cleaning process to identify the key variables within it, this can be conducted using a computer program.
Due to the large variation between measurements/noise
• Observational Data:
Has to also go through an extensive data cleaning process to identify the key variables within the data.
Due to the large variation between measurements/noise
• Self-Report Measures:
Requires more than 1 or 2 items in order to effectively measure the construct it represents and the naturally occurring noise!
Typically, a minimum of 4-5 items should be used.
Sometimes, and only sometimes is 3 sufficient.
Note: These items need to be focused around the construct!!! Variability within the
same scale will not produce reliable measurements.
Do people Want to find reliability within their data?
*It depends on the type of variable you are measuring!
For example,
Q: If you have 3 different self-report measures: Gender, mood, and optimism. Which of these measures will be the most reliable over a three-month period?
A: Gender.
Gender: Is Highly stable demographic variable, the most reliable in terms of test-retest reliability with r = .95.
Psychological: are variables rooted in personality like optimism that have intermediate stability, has moderate test-retest reliability with r = .70.
Mood: Variable that changes frequently, has weak stability, has the lowest test-retest reliability, r = .50.
The Goal of Test-Retest Reliability is Somewhat Ambiguous because it depends on…
“The value will depend on the time between test and retest, the length of the test, what is being measured, and the characteristics of the sample. Some traits are very stable. Others may show some change over time. Thus, there is no absolute value and it will depend on the situation. “
If someone asks you how reliable is your measure you should ask…..
What type? There are two main types of reliability!
(A) Test Retest Reliability
Correlation overtime for the same individuals.
(B) Internal Reliability
The average level of intercorrelation between items
within a scale.
e.g. Cronbach’s Alpha