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61 Cards in this Set
- Front
- Back
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What are the two types of statistics?
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Descriptive & Inferential
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Describe DESCRIPTIVE statistics
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describes, organizes, summerizes (average, mean, standard deviation)
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Describe INFERENTIAL statistics
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generalizing from a large group to a small group
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describe sample
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small group, subset of population
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describe population
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larger group everyone who shares a characterisitc
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What are the two types of statistics?
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Descriptive & Inferential
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Describe DESCRIPTIVE statistics
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describes, organizes, summerizes (average, mean, standard deviation)
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Describe INFERENTIAL statistics
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generalizing from a large group to a small group
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describe sample
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small group, subset of population
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describe population
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larger group everyone who shares a characterisitc
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what is randomization used for?
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used to ensure a representative sample
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constant
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doesnt change in an experiment
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variable
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changes in an experiment
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name the who types of variables
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dependant & independant
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what is an independant variable?
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the variable that the experimenter changes or manipulates
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what is a dependant variable?
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the variable that you (or the experimenter) are measuring
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what is a descrete variable
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finite. ex) number of kids
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what is a continuous varible
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infinite, always able to get more specific ex) time
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What are the four levels of measurement?
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nominal
ordinal interval ratio |
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which is the most simple, which is the most complex?
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nomial-simple
ratio-complex |
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what does nominal measurement do?
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names or categorizes data
ex) room numbers, street, gender 0-tote 1-purse 2-backpack |
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what does ordinal measurement do?
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ranks subjects
ex) places in a race 1st, 2nd, 3rd, etc. |
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what does interval measurement do?
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has equal differences between points
CAN get negative numbers |
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what does ratio measurement do?
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measures things that have an absolute zero point
ex) length, time, etc. |
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what is a Zscore?
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"a deviation score expressed in standard deviation units"
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what does a Zscore allow us to do?
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1.compare scores from the same distribution
2.compate scoares from different distributions |
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percentile rank
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tells percentage of scores that fall at or below your own score
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what is a sampling distribution?
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"A theoretical distribution consisting of the mean scores of all possible samples of a given size from a population"
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explain sample distribution
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-pull out sample to test
-throw back and pull out new sample -continue until you have tested all samples |
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important fact to remember about sampling distributions
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mean of the sampling distribution will always equal the mean of the population
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describe null hypothesis
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Ho
"the results that we get are only due to chance" |
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describe alternative hypothesis
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H1
"the results are due to something other than chance |
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alpha level
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(looks like jesus fish)
cutoff line "The cutoff point where we decide the probability of this being ust due to chance" |
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name the two alpha levels that researchers use, the most common, and why.
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.05 & .01
the most common is .05, because it is the highest that is statistically significant. (easier to get desired results) |
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what happens if we retain the null?
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prove IV is due to chance (wrong)
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name examples of conservative language
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suggest
appears retain |
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examples of not conservative language
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garuntee
prove fact |
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Type I Error
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"falsely reject the null"
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Type II Error
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"fail to reject the null when you should have"
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whats is the probability of making a type I error
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whatever you set the alpha level at
(.05 .01) |
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When to use a one sample t-test
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when study has known population value and only one sample
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when to use an independant groups t-test
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when study has two levels of the 1 IV and 1 DV
(with Independant groups design is used) |
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when to use paren samples t-test
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when study has two levels of the 1 IV and 1 DV
(with repeated measures design used) |
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what are some assumptions of a t-test?
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-populations are normal
-homogeneity of varience |
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what is homogeneity of varience?
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populations we take our samples from have equal variances
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what is robust?
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can violate some assumptions of a t-test and stull use test.
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When to use a one-way ANOVA
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when there are 3 or more levels of the IV, and one DV
(for independant groups design OR repeated measures design) "one independant variable, with more than two groups" |
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why use a one-way ANOVA?
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more efficient
to prevent alpha inflation |
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what is alpha inflation?
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"increased risk of making a Type I error"
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what do repeated t-tests increase the chance of?
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Having a Type I error
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what is between group variability?
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"The means of the group vary from one another"
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What causes the difference between means of groups in "Between group variability"?
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-Treatment (IV)
-individual differences -error |
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What causes within group variability?
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-individual differences
-error |
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what does the F-test do?
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compares between group variability and within group variability
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what does it mean if F=1 as a result of an F-test?
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we retain the null hypothesis
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what does it mean if F>1 as a result of an F-test?
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we reject the null hypothesis
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when do you run a factorial ANOVA?
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Study has two IVs with two or more levels and one DV
(Independant groups design is used) "two or more IVs (each with two or more levels) |
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why do we use a factorial ANOVA?
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when there are two or more IVs (each with two or more levels) because it is very rare, if ever, that just one thing will effect behavior.
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what is a main effect?
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the effect of a single IV by itself in isolation
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define interaction
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"The effect of one Independant Variable depends on the level of another Independant Variable"
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how is interaction shown?
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(A*B) interaction
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