# Stats Mid Term

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1. statistic
science of data
2. individuals/cases
objects being described by set of data
3. variable
any characteristic of an individual and can take on different values
4. quantitative variable
numeric
5. qualitative variable
wordy
6. values
particular things variables take on
7. observational study
observes individual and measures variables of interest but does not influence responses.  used to describe group or situation
8. response
variable that measures an outcome or result of a study
9. sampling
to gain info of whole through one part
10. sample surveys
survery goup of individuals by studying only some of members. it represents the larger group
11. population
entire group of individuals about which we want information (group want to study)
12. sample
part of population from which we actually get the information and use it to draw conclusions about the whole
13. census
sample survey that attempts to include entire population in sample
14. experiments
deilberately imposing some treatment on individuals to observe responses.  can give cause and effect
15. biased
statisitical study that systematically favors certain outcomes.
16. convenience sampling
selection of individuals who are easiest to reach
17. voluntary response sampling
chooses itself by responding to a general appeal (call in)
18. simple random sample
choose a sample of n individuals form the population by a way that every set of n individuals has a chance to actually be selected
19. table of random digits
• long string of digits with two properties...
• 1. each entry is equally likely to be 0-9
• 2. entires are independent of each other
20. parameter
number that describes the population
21. statistic
number that describes a sample
22. parameter is to __________ as statistic is to ______.
population; sample
23. variablility
describes how spread out values are
24. SRS
simple random sample
25. p
proportion (fraction thats divided)
26. p-hat
statistic
27. margin of error
plus or minus 2% points of how close sample stat is to pop parameter
28. 95% confident
truth lies within the margin of error ( what % of all possible samples satisfy margin of error)
29. confidence statements
• fact about what happens in all possible samples and is used to say how trustworthy result of sample is
• 1. margin of error
• 2. level of confidence
30. sampling errors
• errors caused by thw act of taking a sample
• -undercoverage
• -random sampling error
• -biased sampling methods
31. random sampling error
deviation between sample stat and the population paramenter cause by chance in selecting a random sample
32. nonsampling error
• errors not related to the act of selecting a sample from the population
• -processing erros
• -response error
• -nonresponse
33. sampling frame
list of every individual from population
34. undercoverage
occurs when some groups in population are left our of process of choosing the sample
35. processing errors
mistakes in mechanical tasks like arithmatic or entering responses into a computer
36. response error
when subject gives incorrect response  (lie, guess, bad memory)
37. nonresponse
failure to obtain data from individual selected for a sample (cant contact or no coorpation)
38. stratified random sample
• 1. strata - divide sampling frame into distinct groups of individuals
• 2. clusters - take separate SRS in each stratum and combine to make complete sample
39. probability sample
sample chosen by chance
40. response variable
variable that measures an outcome or reult of study (dependent)
41. explanatory variable
variable that we think explains or causes change to response variable (independent)
42. subjects
individuals studied in an experiment
43. treatment
specific experimental condition applied to subjects
44. lurking variable
variable that has important effect on relationship among variables in study but isnt one of explanatory variables studied
45. confounded
when 2 variables have effect on a response variable and cannot distinguish from each other
46. clinical trials
experiment that studies effectiveness of medical treatments on actual patients
47. placebo
dumby treatment with no active ingredients
48. placebo effect
response to dumby treatment
49. double-blind
neither subjects nor testers recording know which treatment was to who
50. randomized comparative experiment
one that compares two treatments and allow us to draw cause and effect and is random and compares two things that are actually operating equally
51. control group
can be placebo group (no treatment at all)
52. control
effects of lurking variable on response, most simply by comparing 2 or mor treatment
53. randomize
use impersonal chance to assign subjects to treatments
54. statistically significant
observed effect of a size that would rarely occur by chance
55. comparative
good, compare in observance
56. matching
combine comparison in creating a control group
subjects who participate but do not follow the experimental treatment
58. dropouts
those hwo begin an experiment that continues over extended period of time then they do not complete it
59. generalizability
accurate of whole population
60. completely randomized
experimental design, all the experiemental subjects are allocated at random among all treatments
61. matched pair design
compares 2 treatments that the pairs of subjects are closely matched as possible
62. block design
random assignment of subjects to treatment is carried out sepaately within each block
63. block
experimental subjects that are similar in some way prior to experiment that is expected to affect response of treatments
64. measure
a property of person or thing that we assign a number to represent the property
65. instrument
make a measurment
66. units
used to record the measurment
67. variable
result of measurement is numberical
68. valid
meassure of a property if it is relevant or appropriate as a representation of that property
69. predictive validity
can be used to predict success on tasks that are related to the property measured
70. bias in measurement
sustematically tends to overstate or understate true value of measured property
71. random error in measurement
repeated measurements on same individual but gives different results
72. reliable
if random error is small
73. average in measurement
several repeated measurements of same individual is more reliable than a single measurement
74. distribution
variable that tells us what values it takes and how often it takes these
75. frequency table
• raw data
• values || frequency
76. roundoff errors
rounded entries dont quite add to total which is rounded seperately
77. pie chart
show how a whole is divided into parts and forces us to see parts that make a whole
78. bar graph
help distinguish tween variables whose values have meaningful numerical scale
79. categorical variable
places individual into one of several groups of categories
80. quantitative varaible
takes numerical values for which arithmatic operations like ading and averaging make sense
81. pictogram
bar graph in whic pictures replace bars and ar not proportional
82. line-graph
to display change over-time and plits each variable against time
83. histogram
distribution of quantitative variable and bars touch
84. center
midpoint of distribution
variability of data (dont count outliers)
86. shape
peaks (unimodal, bimodal, mutlimodal), symmetric
87. right skew (positively skewed)
when the tail goes to the right
88. left skew (negatively skewed)
when the tail goes to the left
89. stemplot
stem is on the left and leaves are on the right
90. median
midpoint of distribution, the # that is positioned half way tween all the observations
91. quartiles Q1 and Q3
midpoints from beginning to median and median to end and divides observations into quarters
92. five number summary
min, Q1, median, Q3, max
93. boxplot
graph of five num sum
94. Mean (x-bar)
average of set of observations
95. mode
most frequent number
96. standard deviation (s)
measures average distance of observations from mean
 Author: karose92 ID: 176354 Card Set: Stats Mid Term Updated: 2012-10-09 00:54:59 Tags: stats Folders: Description: stats 140 midterm (vocab) Show Answers: