C207 OA Exam Questions & Correct
Answers Verified 100% Correct |Latest
Updates|
Measurement Bias - ANSWER -data doesn't represent the study group because of:
1. sample isn't random enough
2. sample isn't big enough
3. sample wasn't inclusive enough, or was too inclusive, to represent study group
i.e. a survey on favorite foods was sent to all renters in a city (didn't include
homeowners so not a "Truly Representative Sample")
Conscious Bias - ANSWER -the subject is biased towards a certain result because
he believes it will benefit him in some way
Information Bias - ANSWER -response bias - people give different ANSWERs
when the response isn't anonymous and confidential
i.e. a boss surveys his own employees to see if they are satisfied with is
performance
conscious bias - questions are deliberately leading or persuading the subject toward
a certain ANSWER
i.e. a survey question reads: "Don't you think it would be better if the gov't
provided free contraception?"
Data Management - ANSWER -cleaning and organizing data
Quality Control in data - ANSWER -reducing and minimizing data errors
clean and organize data
,reduce amount of incomplete data
Two Major Issues with Research Standards - ANSWER -Agreement on best
practices
Ethics
Misuse of Statistics - ANSWER -all the bias. additionally:
1. Assuming that correlation equals causation. CONCLUDES, DETERMINES,
ASSERTS
2. Lack of blinding.
3. Faulty operationalization - unclear testing model, undefined terms, not
coded/categorized.
Probability Theory - ANSWER -informs decision-makers by quantifying risk
Probability of the complement - ANSWER -the probability remaining. if only 2
possible outcomes are possible, then you get probability and probability of
complement.
i.e. if probability is 2/3 then probability of complement is 1/3
Intersection Probability - ANSWER -use the "Multiplication Principle" (multiply
the probabilities)
p of x AND y
p of ALL the following
p of BOTH x and y
p of X GIVEN b
p of X WHEN b
,Union Probability - ANSWER -p of x OR y
p of EITHER x or y
AT LEAST
ANY of the following
add the possibilities
Combination Probability - ANSWER -rule / formula for determining how many
POTENTIAL / POSSIBLE OUTCOMES
Bayes' Theorem (probability) - ANSWER -rule to calculate conditional probability
GIVEN THAT
"If P(A) is the case, then what is the P(B)"
or
"Given event A, what is the probably of event B"
P(A) / P(A|B)
Use median when - ANSWER -data has outliers or is skewed, otherwise you can
use mean
i.e. income for a group that has several outlier millionaires
Use mode when - ANSWER -data is categorical / qualitative
TYPICAL, MOST COMMON
Variance - ANSWER -used to measure risk.
actual - expected
current - prior
higher = greater variation (higher risk)
, i.e. assessing risk in stock portfolio
Standard Deviation (SD) - ANSWER -average distance from the mean. also
computed as variance rooted
average spread between data points
i.e. a surveyor wants to know how much test ANSWERs differ from each other
68/95/99 rule aka "Empirical rule" - ANSWER -rule to estimate data. only works
for normal distributions (unimodal symmetrical)
68.2% of data falls within +1 SD or -1 SD of mean
95.4% of data falls within +2 SD or -2 SD of mean
99.7% of data falls within +3 SD or -3 SD of mean
Z-Scores
68.2% = 1.65
95.4% = 1.96
99.7% = 2.575
for exactly location when provided the mean and std dev, use Z-score formula
Z score formula - ANSWER -Best score to compare to a group average
(score - mean) / standard deviation
i.e. A student scored a 70 on a test with a mean score of 50. The std. deviation is
10. What % of other students scored better?
(70 - 50) / 10 = 2 (2 deviations above mean) leaves 2.15% + .15% on the side
better so 2.3% scored better
Quartiles - ANSWER -Separating data in 4 equal parts based on std. deviation.
Answers Verified 100% Correct |Latest
Updates|
Measurement Bias - ANSWER -data doesn't represent the study group because of:
1. sample isn't random enough
2. sample isn't big enough
3. sample wasn't inclusive enough, or was too inclusive, to represent study group
i.e. a survey on favorite foods was sent to all renters in a city (didn't include
homeowners so not a "Truly Representative Sample")
Conscious Bias - ANSWER -the subject is biased towards a certain result because
he believes it will benefit him in some way
Information Bias - ANSWER -response bias - people give different ANSWERs
when the response isn't anonymous and confidential
i.e. a boss surveys his own employees to see if they are satisfied with is
performance
conscious bias - questions are deliberately leading or persuading the subject toward
a certain ANSWER
i.e. a survey question reads: "Don't you think it would be better if the gov't
provided free contraception?"
Data Management - ANSWER -cleaning and organizing data
Quality Control in data - ANSWER -reducing and minimizing data errors
clean and organize data
,reduce amount of incomplete data
Two Major Issues with Research Standards - ANSWER -Agreement on best
practices
Ethics
Misuse of Statistics - ANSWER -all the bias. additionally:
1. Assuming that correlation equals causation. CONCLUDES, DETERMINES,
ASSERTS
2. Lack of blinding.
3. Faulty operationalization - unclear testing model, undefined terms, not
coded/categorized.
Probability Theory - ANSWER -informs decision-makers by quantifying risk
Probability of the complement - ANSWER -the probability remaining. if only 2
possible outcomes are possible, then you get probability and probability of
complement.
i.e. if probability is 2/3 then probability of complement is 1/3
Intersection Probability - ANSWER -use the "Multiplication Principle" (multiply
the probabilities)
p of x AND y
p of ALL the following
p of BOTH x and y
p of X GIVEN b
p of X WHEN b
,Union Probability - ANSWER -p of x OR y
p of EITHER x or y
AT LEAST
ANY of the following
add the possibilities
Combination Probability - ANSWER -rule / formula for determining how many
POTENTIAL / POSSIBLE OUTCOMES
Bayes' Theorem (probability) - ANSWER -rule to calculate conditional probability
GIVEN THAT
"If P(A) is the case, then what is the P(B)"
or
"Given event A, what is the probably of event B"
P(A) / P(A|B)
Use median when - ANSWER -data has outliers or is skewed, otherwise you can
use mean
i.e. income for a group that has several outlier millionaires
Use mode when - ANSWER -data is categorical / qualitative
TYPICAL, MOST COMMON
Variance - ANSWER -used to measure risk.
actual - expected
current - prior
higher = greater variation (higher risk)
, i.e. assessing risk in stock portfolio
Standard Deviation (SD) - ANSWER -average distance from the mean. also
computed as variance rooted
average spread between data points
i.e. a surveyor wants to know how much test ANSWERs differ from each other
68/95/99 rule aka "Empirical rule" - ANSWER -rule to estimate data. only works
for normal distributions (unimodal symmetrical)
68.2% of data falls within +1 SD or -1 SD of mean
95.4% of data falls within +2 SD or -2 SD of mean
99.7% of data falls within +3 SD or -3 SD of mean
Z-Scores
68.2% = 1.65
95.4% = 1.96
99.7% = 2.575
for exactly location when provided the mean and std dev, use Z-score formula
Z score formula - ANSWER -Best score to compare to a group average
(score - mean) / standard deviation
i.e. A student scored a 70 on a test with a mean score of 50. The std. deviation is
10. What % of other students scored better?
(70 - 50) / 10 = 2 (2 deviations above mean) leaves 2.15% + .15% on the side
better so 2.3% scored better
Quartiles - ANSWER -Separating data in 4 equal parts based on std. deviation.
