Research Methods Flashcards
(47 cards)
Explain reliability and validity?
Reliability– is the consistency of the measurement (the umpire being consistent even if it is not accurate)
“Reliability on the scores! Not the test! TESTS DON’T HAVE RELIABILITY”
Validity- is the accuracy of the measurement or instrument (when the umpire calls a strike and its a strike the call is valid)
What are some tests to measure reliability?
(1) Test re-test
(2) Alternate forms
(3) Internal consistency
(4) Interrater reliability
Define and/or explain the four tests to measure reliability?
(1) Test re-test: repeat measurement and should receive similar results
(2) Alternate forms- prepare alternate versions of the test covering the same content but with different items
(3) Internal consistency reliability: split half reliability; two halves of the test meet the standards of parallel forms
(4) Interrater reliability: obtain ratings from multiple sources, i.e. two researchers
Give an example of observed score vs. true score; and what is the formula that depicts this phenomena?
My actual height is True Score, The height measured on the wall or another person is Observed Score X- observed score t- true score e- error X= t + e
Name and explain the measures of central tendency?
Mean- the average of scores, Sum of X over n.
Median- middle score
Mode- the most frequent
The mean takes into account the magnitude of all the scores, in contrast the median takes into account only the numbers of scores and the values of the middle scores.
In a normal curve how are the percentages distributed?
Mean is at the center, 34% on either side- represents one sd from the mean, then second line is 14%, then finally 2% at the tails.
Where do the mean, median, and mode fall on a positively skewed distribution vs. negatively skewed distribution?
Positively skewed: starting from far right to left: Mean, Median, Mode
Negatively skewed: starting from far left to right: Mean, Median, Mode
What are the three measures of variability?
Range, Variance, and Standard Deviation
What is the range?
R= H - L, highest minus lowest scores. “range of scores are from 1 to 5”
What is variance?
σ2 = Σ(x1 –m)2
N - 1
The average deviation of all the numbers from the mean in squared units.
Whenever we are doing any research we want to explain the variance in people.
What is standard deviation
SD = square root of Σ(x1 –m)2
N - 1
What are the five steps to figure SD?
Step1: find mean: Σ X
Step 2: subtract the mean from each number:
Σ (x – x bar)
Step 3: square of each number (to get rid of negative numbers): Σ (x – x bar)2
Step 4: Variance: Σ(x1 –m)2
N - 1
Step 5: SD: square root of Σ(x1 –m)2
N - 1
What is a Z score?
Raw score that has been transformed into standard deviation units;
A z-score tell you how many standard deviations a raw score is from the mean
i.e. when looking at GRE scores (a z-score of +2 means a score 2 standard deviation above the mean.
z= x - xbar/ sd
What is statistical significance?
Researchers claim their finding is statistically significant when they do not believe that their observed result was due only to chance or sampling error.
Answers the questions: is there a relationship between the IV and the DV? Is it greater than 0?
Rejecting the null hypothesis
What is effect size?
A measure of the strength or magnitude of a relationship between the IV and the DV
What is regression analysis?
A set of statistical procedures used to explain or predict the relationship between a dependent variable and one or more independent variable.
Regression analysis is also used to understand which among the independent variables are related to the dependent variable, and to explore the forms of these relationships.
What is the regression equation formula? Both with and without standardized scores?
Non-standardized scores: y hat = a + bx
With standardized scores: y hat = b1x1 + b2 x2
y hat is the predicted value of the dependent variable
a is the y intercept
b is the regression coefficient or SLOPE; the predicted change in Y given a 1 unit change in x; the amount we will see change in salary from 2.5 gpa to 3.0 gpa.
Describe the components of the regression summary table?
SE Variable R R2 delta R2 Beta b
Accult Stress 0.4 0.16 0.1
Fam Support 0.5 0.25 0.09 0.1
.4 represents that correlation coefficient between SE and AS?
.5 represents the correlation of the combined AS and FS?
What does delta R2 represent? The change between R and R squared (.25 - .16)
Beta column represents the standardized score? And b represents the unstandardized?
Beta’s indicate the unique correlation between each variable and the criterion
When you are doing regression analysis, you have to decide how to enter the x variables. What are three entry methods/procedures?
1) Simultaneously- use this when you want to find how well the variables collectively predict y and which is more important
2) Step-wise- usually the default; use this when you want to show the best set of the predictors
3) Hierarchical- use this when you want to find out how the other variables relate, i.e. I know Acculturative Stress relates, and I want to find out if family support adds anything
What is T-test?
Statistical test used to determine whether the difference between the means of two groups is statistically significant.
Selecting people for your study is an important consideration. What is range restriction?
the more restricted or narrow your scores are on your measures vs your population, the lower reliability. (i.e. African American Women and two clinic where African American Women are recruited- they already have been identified as at risk or receiving treatment so the range will be narrow)
Describe Type I and Type II error
Null hypothesis is TRUE or FALSE (should be rejected)
FAIL to reject it or REJECT it…
TYPE I: When the null hypothesis is TRUE, but it is REJECTED– False Positive, claiming positive outcome or finding when it really was not!
TYPE II: When the null hypothesis is FALSE, but it is NOT rejected. False Negative, claiming there wasn’t any findings when there was.
What is the error rate alpha:α?
α error rate was decided by convention that if the probability of making a Type I error is 5 chances out of 100, .05, or less that’s good, but 6 chances out of 100 is not!
What does t distribution tables tell us?
lower case v?
2Q?
lower case v= degrees of freedom; degrees of freedom for T-test is n - 2
2Q= two tailed test
This table tells us if your T-test yields the corresponding number or higher you can reject the null hypothesis
