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PSY201 9.11.13 To Post

# Stascal terminology varies for sample stascs versus

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Unformatted text preview: to make inferences about… on the basis of a [email protected] sample   Sample: a part of the [email protected] for which a researcher collects data and knows a set of scores 10 9/10/13   Why do we study samples, rather than a [email protected]?   [email protected]   Goal is to make [email protected] or [email protected] about events beyond our reach   Try to study a sample of people who are [email protected] of the [email protected] of interest   Random [email protected] is ideal   From the full [email protected] of interest, randomly select individuals to be included in sample   OCen is [email protected] or impossible to obtain a truly random sample ▪  Instead, try to get a sample that is not [email protected] [email protected] of [email protected] in any known way ▪  Avoid haphazard [email protected][email protected]@cal terminology varies for sample [email protected]@cs versus [email protected] parameters Population Parameter Sample Statistics Scores from entire population Scores of sample only (Usually unknown) (Calculated from known data) µ (mu) M σ (sigma) SD (sigma squared) SD 2 Mean Standard Deviation Variance σ2 11 9/10/13   Probability deﬁ[email protected]: Expected [email protected] frequency of an outcome   Outcome: result of experiment/[email protected]   Frequency: how many @mes something happens   [email protected] frequency: number of @mes something happens [email protected] to the number of @mes it could have happened   Expected [email protected] frequency: what you expect to get in the long run if you repeat the experiment/[email protected] many @mes   Long ­run [email protected] frequency [email protected] of probability vs. [email protected] [email protected] of probability   Probability = Possible successful outcomes All possible outcomes What is the probability of genng a 4 when you roll a die? 1/7 = 0.14 What is the probability of choosing a heart from a deck of cards? 13/52 = 1/4 = 0.25   Range: 0 to 1, also represented 0 ­100%   Probability as the likelihood of occurrence   Impossible to Certain 12 9/10/13   Probability is symbolized as the le]er p, and usually represented as a decimal (0 to 1) rather than a percent   p = .5 represents a 50/50 chance   p < .05 represents “the probability is less than .05”   The normal [email protected] can be thought of as a probability [email protected] 15 70 85 100 115 130   You apply to 20 graduate programs, 10 of which are in clinical psychology, 5 of which are in counseling psychology, and 5 of which are in social work. You get a message from home that you received a le]er from one of the programs. Give the [email protected] that it is from   A clinical psychology program.   A counseling psychology program.   From any other program besides social work. 13 9/10/13   A student wants to study the eﬀect of stress on memory. He posts a sign ­up sheet for anyone willing to [email protected] The student is [email protected]: a.  Random [email protected] b.  Haphazard [email protected] c.  Speciﬁed [email protected] d.  Quota [email protected]   In [email protected]@cal language, a scoop of water drawn from a ﬁsh tank full of tropical saltwater ﬁsh to determine the exact salt content of the water is: a.  [email protected] b.  Parameter c.  Sample d.  [email protected] [email protected]   In a normal curve, approximately __?__ percentage of scores are lower than 2 standard [email protected] below the mean.   In a normal curve, approximately 68% of the scores are between a z ­score of __?__ and a z ­score of __?__.   In a normal curve, what percentage of scores fall within 2 standard [email protected] of the mean? 14...
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