# Jessica

The flashcards below were created by user jchampio on FreezingBlue Flashcards.

1. Statistics is A branch of mathematics focused on
• *organization
• *analysis
• *interpretation of numbers
2. goal of statistics
to organize and interpret data
3. Characteristics or conditions that can change.
• Variables
• (most research begins with a question about the relationship between 2 variables for a specific group of individuals.)
4. The entire group of individuals is
population
5. examples of population
6. selected to represent the population
(populations are usually so large that researchers cannot examine the entire group)
Sample
7. measurements obtained in a study
Datat
8. Two types of Statistical Methods
• *Descriptive statistics
• *Inferential statistics
9. Organize and summarize data
• Descriptive statistics
• examples:
• * tables, grapshs, average score
10. parameter
a descriptive value for a population
11. Statistic
a descriptive value for a sample
12. Use sample data to make general conclusions about population
Inferential Statistics
13. 1. a sample is only a part of the whole _____
2. sample data provide limited info about the___
3. sample statistics are imperfect representatives of the corresponding ___ parameters
population
14. the discrepancy between a sample statistic and its population parameter is called
Sampling error
15. 2 classifications of variables
• 1. discrete variables
• 2. continuous variables
16. discrete variables
• indivisible categories
• examples
• *gender
• *car*sex
17. infinitely dividable
• Continuous variables
• examples
• *height,pain, time, weight
18. to establish relations between 2 variables...
• *Variables must be measured
• *Variables must be classified into one category
19. 2 scales of measurement
• 1.nonimal scale
• 2.ordinal scale
• 3.interval scale
• 4.ratio scale
20. an unordered set of categories
• Nominal scale
• examples
• *gender
• *martial status
21. an ordered set or categories
• Ordinal scale
• example
• *horse races, contests with places 1st, 2nd, 3rd
22. an ordered series of equal-sized categories
• Interval scale
• examples
• *6-point likert scale (rate 1-10)
• *IQ
23. An ordered series of equal-sized categories
A value of zero indicates none of the variable
• Ratio Scale
• examples
• *lenth, volume
24. 3 major classifications
• - experiemental studies
• -correlation studies
• -quasi-experiemetal studies
25. one variable is manipulated IV
a second variable is observed for changes DV
all other variables are controlled to prevent them from influencing the results.
Experimental Studies
26. what is teh goal of experimental studies ?
and give an example?
• to establish a cause-effect relationship between the IV and the DV
• - i.e., does noise decrease test scores
• amount of noise=IV
• test scores=DV
• environment and time = controlled
27. observe two variables as they exist naturally..
I.e., is high school GPA related to SAT scores?
Correlation Studies
28. similar to an experiment but is missing either the manipulated IV or the control necessary for a true experiment
• Quasi-experimental study
• - the IV is usually a pre-existing variable
• -i.e., parent child relationship, cancer.
29. the number of scores with a value
frequency
30. the pattern of frequencies over different values
frequency distribution
31. frequency tables
• make sense of a set of numbers.
• show how many times a number is used
32. bar graph.
provide a picture of distribution
histograms
33. line graph
frequency polygons
34. a frequency distribution with 2 or more high points
multimodal
35. Negative Skew
points to the left, peak is in the right.
36. ceiling effects means what skew?
and if the table was test grades what would the result tell you
ceiling effect is a negative skew, most scores piled up at the right meaning the test was too easy.
37. floor effect means what? and what a floor effect mean for a test?
floor effect is a positive skew. most scores piled up at the left, meaning the test was too hard.
38. a representative or typical value in a distribution
Central Tendency
39. 3 meausres of central tendency
• 1. mean
• 2. median
• 3.mode
40. of the best measure of central tendency.
most frequently reported in research articles
think of the mean as the "balancy point" of distribution.
Mean
41. Middle value in a group of scores.
half the scores are above, half the scores are below (aka the "50h percentile")
• Median
• - unafftected by extreme individual scores
• - unlike the mean prefereable as a measure of central tendency when a distribution has EXTREME scores or when SKEWED.
42. most common single number in distribution.
IF distribution is symmetrical and unimodal ____ = the mean
- typical way of describing central tendency of a nominal variable
Mode
43. the second way to describe numbers
Dispersion
44. 3 measures of dispersion
• 1.range
• 2.vairance
• 3. standard deviation
45. simpliest measure of dispersion. The distance from the lowest to the highest score
Range
46. how spreadout the scores are from the mean.
variance
47. another measure of variation. Roughly the average amount scores differ from the mean. used more widely than variance.
standard diviation
48. are standardized scores used to compare numbers from different distributions.
describe particular scores. where a score fits in a group of scores in a distribution.
• Z scores
• - raw scores are meaningless.
• -i.e., i got a score of 565 in meaningless.
• vs, i got a z-score of 1.64
49. z scores continued.
the sign of the z score (- or +) indeciateds. the score is located above the mean (+). or below the mean (-).
the value of z indicates the number of standard deviation between x and the mean of distribution.
• -z score of 1.0 is one SD aboce the mean
• -z score of -2.5 is two and a half SDs below the mean
• -z score of 0 is AT the mean
50. measure and describe the relationship between 2 variables
• Correlation
• - X = one score
• -y = other score
• pair of XYsocres is usually from the same subject
51. descriptive statistic
- single number (e.g. r=.78)
- summarizes and describes a relationship
correlation coefficient
52. Coffee and nervousness, are correlation coefficient but they DONT ____ each other
• COEFFICIENTS DO NOT CAUSE EACH OTHER.
• need a true experiment
53. as X scores increase, Y scores also increase
positive linear relationship
54. as X scores increase, Y scores decrease
negative linear relationship
55. as X scores increase, Y scores do NOT only increaseor only decrease.
- at some point the Y scores change their direction of change
• non-linear relationships
• (curvilinear)
56. The larger the absolute value of the correlation coefficient, the _____ the relationship
• Stronger.
• the sign only indicates the direction of the linear relationship, NOT the strength.
• i.e., .78 and -.78 are strong relationships
57. describe relationships of 2 variables in a sample luck of the draw may produce a correlation, so you'll also need statistical significance.
correlatoin coefficients
58. only accept a correlation as "real" if it's significiant.
"income was related to agression (r=-.78, p<.05).
what does this tell you...
• that it is significant.
• that there is less than a 5% chacne that the correlation in a population is NOT REAL
• (which means a 95% chance that it is real)
59. Research articles report: Correlation coefficientts : put single correlations _____
• in text.
• i.e., there was a significant correlation (r=.51, p<.05) between age and depression.
60. Research Articles Report:
Correlation Coefficients, put several correlations ____
• in table.
• (variables listed down left and across top)
61. The correlation of each pair of variables is shown in tables the table is called a ____
Correlation Matrix
62. Correlations help in making ____
• predictions
• e.g., prediction college GPA from HS SAT
63. what is the variable being predicted from
predictor variable (X)
64. whats the variable being predicted to
criterion variable (Y)
65. social scientists call prediction
• regression.
• - can predict using 2 scores or raw scores
66. prediction using 2+ predictor variables is called
• multiple regression
• *** mutiple regression and correlation are frequently reported in research articles, so its important to have a general understanding of them.
 Author: jchampio ID: 62868 Card Set: Jessica Updated: 2011-02-05 03:36:09 Tags: Statistics Folders: Description: Exam Chapters 1-3 Show Answers: