| Terms |
Definitions |
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MSw
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SSw/dfw
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mode
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Most common value
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ORDINAL
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Attributes can be ordered
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Curvilinear
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Correlation is ineffective with curvilinear because it works with linear relationships
-Make it effective by drawing line (range restriction)
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discrete
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numerical data sets where possible values are isolated points
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population later?
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india will surpass the us.
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correlation ignores
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distinction between explanatory and response variables.
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No
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Can you prove cause/effect with an observational study?
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INTERVAL DATA
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-QUANTITATIVE
-EXAMLE IS TEMP. DIFF B/C 60 DEG. AND 61 DEG. IS THE SAME AT 80 DEG. AND 81 DEG.
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Arithmetic Scale
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Distances on the Y-axis are proportional to the magnitude of the variable being displayed on this scale.
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Outlier
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An individual that falls outside the overall pattern
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beta
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the second letter of the Greek alphabet (β, B).
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test statistic
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statistic used to test a hypothesis
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double blind procedure
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an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have recieved the placebo.
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Expected Values
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Expected Values = (valueof event1) x (prob of event 1) + (value of event 2)X(prob of event 2)
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Define "mode."
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The mode is the most frequently occurring score in a distribution
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INFERENTIAL STATISTICS
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Techniques that allow us to study samples and make generalizations or inferences about the populations from which they were selected
- Making Inferences
- Hypothesis Testings
- Determining Relationships
- Making Predictions
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standard deviation
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measure of dispersion in a frequency distribution
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Statistically Significant
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When an observed difference is too large to believe that it is likely to have occurred naturally
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right skewed
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values are more spread out to the right side
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Frequency distribution
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a tabular summary of data showing the frequency of items in each of several classes
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adroit
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expert or nimble in the use of the hands or body.
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Construct validity is..
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the degree to which the test actually tests what you want it to. the truthfulness of the measures
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Continuous quantitative variables
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-can take on any value along an interval
-applicable when there are no gaps between the exact values which these variables can take on, such as weight, height, volume, or distance.
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How are you going to get your information from your sample?
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Observational Study: observe individual and measure variables of interest but does not attempt to influence response. (e.g. stand back and watch)Experiment: imposing some type of treatment on individual in order to observe their response.Anecdotal Evidence: Not good science (e.g. Dateline)
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Theory is a set of related -- about the causes of a -- and the -- that specify how - - --.
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assumptions phenomenon, rules specific causes act.
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the distance between two mean in standard deviation units.
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When should you reject the null hypothesis?
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How do you determine F-crit for comparisons?
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You always use 1 for degrees of freedome in the numerator and the degrees of freedom for your Df s/a
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MGF
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E(e^(xt))
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symmetric
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mean = median
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mutually exclusive
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events that have no outcomes in common
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QUANTITATIVE VARIABLES
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Numeric
Can be represented numerically
(height, age)
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dependent variable
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the experimental factor-in psychology that is being measured; the variable that may change in response to manipulations of the independent variable
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Pareto Chart
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Displays categorical data, with categories displayed in descending order of frequency, so the most common categories appear first.
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dependent variables
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the outcomes that are measured
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mean
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this measure of center is not resistant
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MODE
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OCCURS MORE THAN ONCE AND MORE FREQUENTLY
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Median
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Middle value in sorted array. Pro: Good when extreme data values exist. Con: Ignores extremes and can be effected by gaps in data values.
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direct assocaition
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a positive direction or association means that, in general, as one variable increase, so does the other. When increase in one variable generally correspond to decreases in the other, the assocatiation is negative
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first rule of data analysis
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plot the data.
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false consensus effect
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the tendency to overestimate the extent to which others share our beliefs and behaviors
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Qualitative data
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Values that can be placed into nonumerical categories
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Area Principle
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In a statistical display, each data value should be represented by the same amount of area.
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POPULATIONS
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The entire set of individuals we are interested in studying
(ex) - SAT scores of incoming UM freshmen
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deviation
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difference between one of a set of values and some fixed value, usually the mean of the set
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Census
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A sample that consists of the entire population
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condition for normal distribution
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1.data values clustered near mean= single peaked2.Values spread evenly around mean making symmetric3.Large deviation from mean becomes incresingly rare= producing tapering tails4.Indiviual data results from comnination of many different factors such as genetic and enviormental factors
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Cross-Sectional data
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data collected at the same or approx the same point in time.
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probability distribution
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distribution of all values of a random variable with an indication of their probabilities
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An interaction is...
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...when the effect on one factor is not the same as the effect on all levels of another factor
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STATISTICS
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Values that describe a SAMPLE
(ex) the average SAT score for every
tenth freshman from an
alphabetical list of their last
names
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Why are experiments better than observational studies?
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Give good evidence for causation.Study the combined effects of several factors (interactions between factors can be very important)Control the effects of lurking variables (these get in the way of variables being studied)
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Ethics of Experiments with Humans:
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Planned studies need to be reviewed by board.All subjects must give their informed consent before data is collected.All individual data must be kept confidential. Only summaries can be made public.(Anonymity: researcher doesn't know subjects)
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The standard deviation of the population.
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What is another name for the standard deviation of the distribution of sample means?
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Lower tailed test (Also called a left-tailed test):
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A test with “<” in the alternative hypothesis. This is a one-sided test.
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Quantitative
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numerical value
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INTERVAL
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Distance is meaningful
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Variable
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any characteristic of an individual
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multiplication rule
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method for finding the probability that both of two events occur
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Cluster Sample
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Everyone in a group participates
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Treatment
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A condition applied to the experimental unit. i.e., a new drug is administered to patients.
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variance
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the square of the standard deviation.
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Distribution
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way values are spread over all possiable values
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graphs
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frequency always on y, variable always on x
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Null Hypothesis
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A hypothesis that the difference between two population means is zero or null.
Symbol for the Null Hypothesis = Ho
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probability
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likelihood of the occurrence of an event
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Inference
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Using results from a sample statistic value to draw conclusions about the population parameter.
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control group
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an experiment is the group of subjects who do not receive the treatment being tested
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Extrapolation
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The use of a regression line for prediction for outside the range of values of the explanatory variable x that you used to obtain the line. (Such predictions are often not accurate)
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stacked bar graphs
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compares the contribution of each value to a total across categories.
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conditional probability
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the probability that an event will occur under the condition that another event occurs first: equal to the probability that both will occur divided by the probability that the first will occur.
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convenience sampling
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choosing a sample due to ease of sampling
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Steps in Statisitcal study
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1 identify goal2 choose sample3 collect data4 use sample to make inferences5 draw conclusions
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Bayes' Theorem
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P(A|B) = ( P(B|A)P(A)) / P(B|A)P(A) + P(B|~A)P(~A)
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range
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set of all values attained by a given function throughout its domain
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Left Skewed
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Value are more spread out n the left side
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Level of confidence:
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The percent of the time that the confidence interval estimation procedure will give you intervals containing the value of the parameter being estimated. (Note: This can only be defined in terms of probability as follows: “The probability that the confidence interval to be computed (before data are gathered) will contain the value of the parameter.” After data are collected, level of confidence is no longer a probability because a calculated confidence interval either contains the value of the parameter or it doesn’t.)
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For which types of scales can the mean be used?
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Interval and Ratio
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Why is it important to identify an outlier?
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-might be incorrectly recorded value-might be a data value that was incorrectly included-might be a correctly recored data that belongs in data set
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The standard deviation is the square root of the variance.Another answer: The variance is the standard deviation squared.
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Name 2 advantages of using the standard deviation instead of the range as a measure of variability.
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Why is the mean a poor measure of central tendency for a skewed distribution?
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A skewed distribution has outliers in the tail. Outliers can make the mean unrepresentative of the distribution as a whole.
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