Stats Flashcards

Terms Definitions
Direct relationship
In this kind of relationship, those who score high on one variable tend to score higher on the other, & vice versa
Positive relationship
See direct relationship
Indirect (inverse) relationship
Those who score high on one variable tend to score high on another.
Negative relationship
See inverse relationship
Causal relationship
Est correlation does not necessarily establish causal relationship.
Pearson product moment correlation coefficient
The full, formal name of pearson's r. Ranges from -1.00 to 1.00. Both -1.00 and 1.00 indicate a perfect relationship.
Interpretation of pearson's r
Varies depending on type of study.
Pearson's r
Not a proportion. Thus multiplying it by 100 does not yield a percentage.
Test reliability
One way to examine test reliability is to administer the same test twice to a group of participants without trying to change the participants between administrations of the test - then correlate.
Coefficient of determination
r squared. When r2 is converted to a percentage it indicates how much variance on one variable is accounted for by the variance on the other.
Variance explained
r2 x 100. Aka variance accounted for.
Illustrates correlation between two variables.
Exception to the overall trend.
Multiple correlation coefficient
The symbol for a multiple correlation coefficient is upper case italicize R. A multiple correlation coefficient has the same basic characteristics as r. Determines the degree of relationship between a culmination of two predictors.
Linear Regression
A Regression analysis that assumes that the predictor variable is related to the criterion variable through a linear function
Truncated range
A range of cases that lacks one or both ends of the distribution of values
Restricted range
Limitation by researcher– Via sampling, measuring Procedures, or other aspects of experimental design – of the full range of total possible scores that may be obtained to only a narrow, limited portion of that total
Curvilinear correlation
A functional relationship between variables that is not a straight line form when depicted graphically
Random sampling
-yields an unbiased sample; names can be drawn to obtain a random sample; a table of random numbers may also be used to draw a random sample; to use a table of random numbers give each person in the population number name
Stratified random sample
Draw participants at random separately From each stratum
Multistage random samples
May be used in large-scale studies
Random cluster sampling
Existing groups of participants are drawn. All members of population must belong to a cluster
Sampling Errors
A random sample may differ from a population in important aspects by the luck of the draw
Sample size
The larger the sample, the smaller the sampling errors and the greater the precision; increasing sample size produces diminishing returns; the smaller the anticipated difference in the population the larger the sample should be; for populations with very limited variability even small samples can yield concise results. The more variable the population the larger the sample size should be. When studying a rare phenomenon large samples are usually required. Large samples do not correct Four bias
The larger the sample the smaller the sampling errors and the greater the precision
Central limit theorem
According to this theorem the sampling distribution of Means is normal
Standard error of the mean
The standard deviation of the sampling distribution is known as the standard error of the mean
Sampling distribution of mains
A large number of means
Margin of error
The standard error of the main is a margin of error
Confidence interval for a mean
Confidence interval assist and interpreting means that are subject to random errors. they cannot take bias into account. Using large samples keeps the standard error of the mean and the confidence interval small
Point estimate
A single estimated numerical value of the population parameter
Interval estimate
An estimate range of likely values for a given population parameter
Observed difference
The difference a researcher Obtains. It may not represent the true difference because of the influence of random sampling error.
Significance tests
Test of the null hypothesis
P value
Significance level. The probability of rejecting the null hypothesis when it is in fact true. – Such as making a type one error
Alpha level
The probability level for rejecting the null hypothesis
Decision error
Type one error: reject the null hypothesis when it is true – type two error: felt to reject the no hypothesis when it does false
About the population
Testing the null hypothesis about the population
One tailed significance test
For directional hypothesis
Two-tailed significance test
nondirectional hypothesis
T test
Tests the difference between two sample means for significance
Statistically significant
Hey synonym with rejecting the null hypothesis
Not significant (n.s.)
Failure to reject the null
Symbol for Pearson product moment correlation coefficient
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