IDS 270 EXAM 1 QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026
What is the formula for finding residuals? - Answers y-yhat=residual
When do you know a residual graph is over predicting? - Answers When the point on the residual
graph is below the x-axis, meaning that it's negative.
When do you know a residual graph is under predicting? - Answers When the point on the residual
graph is above the x-axis, meaning it is a positive number
How do you know a relationship between x & y is positive? - Answers If the slope is positive, the graph
is positive, so that means it's a positive relationship between x & y
How can you characterize the strength of the relationship between x & y? - Answers By calculating
(r)^2. The closer r^2 is to 1, the stronger the relationship is.
If x increases by 1, what is the predication for the change in y? - Answers The change in y is dependent
on the amount of regression.
If you: roll even on a red die, and roll an odd on a green die, these are __________ - Answers
independent
If you: roll an even on red and roll an odd on red, these are ____ - Answers disjoint
Formula for the union of two probabilities? - Answers Pr(A U B)= P(a) + P(b) - Pr(A and B)
Formula for: Pr(A and B)? - Answers P(a) * P(b)
How do you know if two parts to a probability problem are independent of each other? - Answers If
Pr(A and B) = P(a) * P(b) = Pr(A and B)
Population Distribution - Answers Entire Population being used
Sample distribution - Answers Initial samples taken from population distribution
Sampling distribution - Answers Averages from all samples taken
What shape is related to Central Limit Theorem? - Answers Bell shape
Finding the Standard Deviation based on C.L.T - Answers S.D of population / Root( # in each sample
If you compare two spreads, which number will be a tighter spread, big or small number? - Answers
Smaller number
What method do you use in order to get: What % of test takers can expect 700 or less - Answers X -->
Z --> %
Ex. General intelligence test has mean of 600, standard deviation of 60. what is percentile score for an
exam of 700 (what percent of test takers get 700 or less) (x < 700),
x is 700,
z= (700-600)/60= 1.66
Pr(z<1.66)
z= 1.6 on table a
left to right- on top is for hundreths place. which is .06
What method do you use in order to get: What score is necessary to reach 90th percentile - Answers
% --> Z --> X
ex.
general intelligence test mean of 600 and a standard deviation of 60. what score is necessary to reach
90th percentile?
.9 in BODY of table A is 1.28( the value is .8997 closest to .9) so solve 1.28=(x-600/60) leads to 676.8
In order to figure out what score is necessary to reach a certain percentile? What do you need to use
to convert to % to the number needed for the equation? - Answers Table A
When talking about X --> Z --> % and vice versa; Format for (___ , ___) is - Answers (mean, standard
deviation)
Formula to compute X --> Z --> % and vice versa - Answers (score-mean)/(Standard Deviation)
When is Simpson's Paradox proven? - Answers When the details disprove the conclusions drawn from
the face-value data
What is a sample? - Answers Amount of people tested. ex sample 40 voters from the population of
ameri ca
What is a statistic? - Answers a number calculated from a sample . Average score of testees.
What is a parameter? - Answers a number that exists in a population. Ex. average height of all women
in america
What is a skyscraper? - Answers All data in one category
What is a pancake? - Answers Too many categories = not a lot of data
What does it mean to minimize chart ink? - Answers Cleaning up the chart
What is the formula for finding residuals? - Answers y-yhat=residual
When do you know a residual graph is over predicting? - Answers When the point on the residual
graph is below the x-axis, meaning that it's negative.
When do you know a residual graph is under predicting? - Answers When the point on the residual
graph is above the x-axis, meaning it is a positive number
How do you know a relationship between x & y is positive? - Answers If the slope is positive, the graph
is positive, so that means it's a positive relationship between x & y
How can you characterize the strength of the relationship between x & y? - Answers By calculating
(r)^2. The closer r^2 is to 1, the stronger the relationship is.
If x increases by 1, what is the predication for the change in y? - Answers The change in y is dependent
on the amount of regression.
If you: roll even on a red die, and roll an odd on a green die, these are __________ - Answers
independent
If you: roll an even on red and roll an odd on red, these are ____ - Answers disjoint
Formula for the union of two probabilities? - Answers Pr(A U B)= P(a) + P(b) - Pr(A and B)
Formula for: Pr(A and B)? - Answers P(a) * P(b)
How do you know if two parts to a probability problem are independent of each other? - Answers If
Pr(A and B) = P(a) * P(b) = Pr(A and B)
Population Distribution - Answers Entire Population being used
Sample distribution - Answers Initial samples taken from population distribution
Sampling distribution - Answers Averages from all samples taken
What shape is related to Central Limit Theorem? - Answers Bell shape
Finding the Standard Deviation based on C.L.T - Answers S.D of population / Root( # in each sample
If you compare two spreads, which number will be a tighter spread, big or small number? - Answers
Smaller number
What method do you use in order to get: What % of test takers can expect 700 or less - Answers X -->
Z --> %
Ex. General intelligence test has mean of 600, standard deviation of 60. what is percentile score for an
exam of 700 (what percent of test takers get 700 or less) (x < 700),
x is 700,
z= (700-600)/60= 1.66
Pr(z<1.66)
z= 1.6 on table a
left to right- on top is for hundreths place. which is .06
What method do you use in order to get: What score is necessary to reach 90th percentile - Answers
% --> Z --> X
ex.
general intelligence test mean of 600 and a standard deviation of 60. what score is necessary to reach
90th percentile?
.9 in BODY of table A is 1.28( the value is .8997 closest to .9) so solve 1.28=(x-600/60) leads to 676.8
In order to figure out what score is necessary to reach a certain percentile? What do you need to use
to convert to % to the number needed for the equation? - Answers Table A
When talking about X --> Z --> % and vice versa; Format for (___ , ___) is - Answers (mean, standard
deviation)
Formula to compute X --> Z --> % and vice versa - Answers (score-mean)/(Standard Deviation)
When is Simpson's Paradox proven? - Answers When the details disprove the conclusions drawn from
the face-value data
What is a sample? - Answers Amount of people tested. ex sample 40 voters from the population of
ameri ca
What is a statistic? - Answers a number calculated from a sample . Average score of testees.
What is a parameter? - Answers a number that exists in a population. Ex. average height of all women
in america
What is a skyscraper? - Answers All data in one category
What is a pancake? - Answers Too many categories = not a lot of data
What does it mean to minimize chart ink? - Answers Cleaning up the chart
