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psyc312-9
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To calculate z-score
Fromale for z-score to data value
X = µ + (zσ)
3 types of probability
subjective (personal judgement)
Analytic/Theoretical - study all possible outcomes
Expected relative frequency (Empirical) - on the long run, average
The Addition Rule
given mutually exclusive events, sum the probabilities
keyword
: OR
Multiplication Rule
for joint probabilities
keyword
: AND
Chi Square Goodness of Fit
Used to test frequency distributions for ONE dimension
E
_{i}
= np
_{i }
|| df = (k-1)
Chi Square: Contingency
E
_{r,c }
=
(sum of Row) x (sum of column)
sample size
df = (r-1)(c-1)
When do we reject the null?
x
^{2}
(observed) > x
^{2}
(critical), reject the null
Sampling Error
Random variability btwn observations or statistics due to chance
Sampling distribution
The distribution of a statistic over repeated sampling from a specified population
properties of Sample Means
the mean of the sample is equal to the population mean (no calculation)
the standard deviation of the sample is (standard error of the mean)
Variance formula
The Null Hypothesis
The hypothesis that the manipulation had no effect.
always contains = or ≤ or ≥
The alternative hypothesis
always contains ≠, < or >
The critical values
represent the point at which we reject the null
we reject the null when we exceed the critical value
2 types of hypothesis tests
One tailed: one direction for rejection; left or right tailed
2 tailed: rejects null when value is too extreme in either direction; non directional
Decision based on a p-value
If p ≤ α (in critical region), reject the null
If p ≥ α (not in critical region), fail to reject the null
Types of errors
Type I error occurs if the null hypothesis is rejected but it's actually true (most serious)
Type II error occurs when the null hypothesis is not rejected but it's actually false
Author
ctryhurn
ID
25317
Card Set
psyc312-9
Description
psyc
Updated
2010-06-30T14:22:43Z
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