Psych research methods exam 2 flashcards
What are common ways of establishing reliability?
- Alternate form reliability:
- Test-retest reliability
- Measures of internal consistency
- Interrater reliability
Alternate form reliability
When you develop 2 versions of a measure, give them both to the same group of people, then correlate them.
Test-retest reliability
When you have one version of exam, give it to the same group of people a
2 different intervals
Measures of internal consistency
Measures of much items correlate with one another
Split-half reliability
Cronbach’s alpha
Split-half reliability
data collected is split randomly in half and compared, to see if results taken from each part of the measure are similar
ex: Test split in half, class take each half and the results are correlated
Cronbach’s alpha
Average of all the ways you can split half an exam
Inter-rater reliability
Kappa
determine how much raters agree with each other
Reliability coefficient of ways to establish reliability
Reliability of coefficient of at least 0.7 for all the methods of reliability except for kappa
Kappa: 0.4-0.75 is good for reliability
Population
Collection of units to which we want to generalize a set of findings or a statistical model too
Representative sample
Smaller collection of units from a population used to determine truths about that population
Random selection
Randomly select people from a population
Random sample
Each individual of the population has an equal chance of being selected
In a random sample, the probability of people have to stay the same
Parameter
A value, usually a numerical value, that describes the entire population
The value is derived from measurements of the individuals in the population
Statistic
A value, usually a numerical value, that describes a sample
Derived from measurements of the individuals in the sample
Statistical notation
Scores are referred to as X and Y
Collecting data on age and number of Facebook friends, you label age as X and friends as Y
N refers to the number of scores in a population
n is the number of scores in a sample
Sigma (summatation)
Add a set of scores from the sample
Summatation
Done after operations
- in parenthesis
- Squaring
- multiplication
- division
Summation is done before
Addition
Subtraction
What is a frequency distribution table
Representation that tells the frequency of different scores in your sample
Function: Organizes all the data so that the complete distribution can be viewed all at once
What are examples of frequency distribution tables and what are they used for?
Polygon or histogram for continuous data
Bar graph for categorical data
How to differentiate between a bar graph and histogram
Bar graph has spaces between them and is only used for categorical data
while histograms are used for continuous data
Statistical notation
Scores referred to as x and y
N refers to number of scores in a population
n is the number of scores in a sample
Σ stands for summation stand for summation and is when the set of scores are added up
Summation
Represented by Σ
Done after PEMD
Done before AS
What are the measures of internal consistency
Split-half reliability
Coefficient/Cronbach’s alpha
Bar graph
graph that presents categorical data with rectangular bars with heights proportional to the values that they represent.
Histogram
chart that plots the distribution of a numeric variable’s values as a series of bars
What are the four characteristics to look for in a frequency distribution
- Shape
- Location
- Spread
- Sample size
Types of shapes in a frequency distribution
Modality
Symmetry
Skew (positive or negative)
Slope-Kurtosis (leptokurtic or platykurtic)
What is the location of a frequency distribution?
A measure of where the bulk of data sits on the number line and where the central tendency is
Central tendency
A statistical measure where a single score defines the center of a distribution
What is the purpose of the central tendency?
Describe the distribution by identifying its center
Find the single score that best represents the entire group
What are the measures of central tendency?
Mean
Median
Mode
What happens to the mean when you change the value of a score or add/remove a value?
The mean changes unless the score added or removed is equal to the mean
What happens to the mean when you add or subtract a constant from each score
Changes the mean by the same constant
What happens to the mean when you multiply or divide each score by a constant?
The mean would also be multiplied or divided by that constant