Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
STATS 305 CALCULATIONS EXAM
QUESTIONS AND ANSWERS
How do you describe a sample ? - ANSWER✔✔-By describing the Mean, Medium, and how each unit
deviates from the mean (via standard deviation)
How do you find the standard deviation - ANSWER✔✔-1. subtract each unit by the mean to "center the
data" ( 𝑥m−𝑥̅ )
2. take the sum of all the squared centered data to get the "sum of squares" Σ ( 𝑥m−𝑥̅ ) ^2
3. divide that by df to get the "variance"
4. square root the whole equation to get "the standard deviation"
what does "centering the data" do when you calculate standard deviation - ANSWER✔✔-it converts all
the data to the positive or negative deviations from the median. On a chart all the units would fall on a
line on the x axis, centered around the median.
Why do you square the deviations when you calculate sum of squares - ANSWER✔✔-if we added all the
deviations together without squaring them we would get 0. We need a positive number.
why do you divide by n-1 when you calculate variance - ANSWER✔✔-n-1 is used for any sample under
30. It accounts for the total variance in the population
what determines how large or small the sum of squares will be in a given data set - ANSWER✔✔-sample
size
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,Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
how does the variance equation change if you were calculating the variance within your sample alone
(and not for the population?) - ANSWER✔✔-you could divide by n instead of n-1
why do you need to square root the variance to get the standard deviation - ANSWER✔✔-the value lies
beyond the Y scale
How do we find if there is a relationship or correlation between certain variables - ANSWER✔✔-1. plot
the variable
2. calculate correlation coefficient
How do you calculate the correlation coefficient - ANSWER✔✔-1. center the data for both variables (xm-
xbar) x (ym-ybar)
2. calculate the "sum of products", add all units deviated sum scores
3. calculate the covariance by dividing this by n-1
4. calculate the correlation coefficient by dividing by the product of the two standard deviations
what is the range of values that the correlation coefficient includes? - ANSWER✔✔--1 to +1
How do we interpret correlation coefficients? - ANSWER✔✔-1. strength, The closer to 1 the stronger
2. directionality, - is negatively correlated, + is positively correlated
What are the benchmarks for weak, moderate, and strong relationships ? (according to Cohen) -
ANSWER✔✔-r>.1 = weak relationship
r>.3 = moderate relationship
r>.5= strong relationship
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,Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
what strength? r>.1 - ANSWER✔✔-weak relationship
what strength? r>.3 - ANSWER✔✔-moderate relationship
what strength? r>.5 - ANSWER✔✔-strong relationship
what are the univariate descriptive statistics - ANSWER✔✔-mean, sum of squares, variance, standard
deviation
what are the bivariate statistics - ANSWER✔✔-sum of products, covariance, correlation
what does univariate mean - ANSWER✔✔-a type of inferential statistics that consists of observations on
only a single variable
The main purpose of univariate analysis is to describe the data and find patterns that exist within it.
ex. finding mean, median, mode
what does bivariate mean - ANSWER✔✔-a type of inferential statistics that deals with the relationship
between two variables
what are parameters - ANSWER✔✔-a value that describes the population
what are estimates - ANSWER✔✔-a value that describes the sample
is 𝑥̅ a estimate or parameter - ANSWER✔✔-estimate, it describes a sample
Research questions are usually about... - ANSWER✔✔-the population
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what is Descriptive Statistics - ANSWER✔✔-statistics which summarize/describe properties of the sample
(or the population if we gather data from the entire population)
what is Inferential Statistics - ANSWER✔✔-statistics which draw conclusions/inferences regarding the
properties of the population, but based only on sample data
is 𝑥̅ a descriptive or inferential statistic - ANSWER✔✔-descriptive
if we compare 𝑥̅ to μ is it a descriptive or inferential statistic - ANSWER✔✔-inferential
How do you know which statistical analysis is important - ANSWER✔✔-Depends on
1. Study design/research question
2. Types of variables (level of measurements, distribution)
3, Whether assumptions of the analyses are met
What are variables - ANSWER✔✔-a characteristic that varies across observations
ex. age
are variables columns or rows in spreadsheets - ANSWER✔✔-columns
what is the independent variable - ANSWER✔✔-the variable the research is manipulating
ex. treatments
what is dependent variable - ANSWER✔✔-the variable we are measuring in response to the treatment
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STATS 305 CALCULATIONS EXAM
QUESTIONS AND ANSWERS
How do you describe a sample ? - ANSWER✔✔-By describing the Mean, Medium, and how each unit
deviates from the mean (via standard deviation)
How do you find the standard deviation - ANSWER✔✔-1. subtract each unit by the mean to "center the
data" ( 𝑥m−𝑥̅ )
2. take the sum of all the squared centered data to get the "sum of squares" Σ ( 𝑥m−𝑥̅ ) ^2
3. divide that by df to get the "variance"
4. square root the whole equation to get "the standard deviation"
what does "centering the data" do when you calculate standard deviation - ANSWER✔✔-it converts all
the data to the positive or negative deviations from the median. On a chart all the units would fall on a
line on the x axis, centered around the median.
Why do you square the deviations when you calculate sum of squares - ANSWER✔✔-if we added all the
deviations together without squaring them we would get 0. We need a positive number.
why do you divide by n-1 when you calculate variance - ANSWER✔✔-n-1 is used for any sample under
30. It accounts for the total variance in the population
what determines how large or small the sum of squares will be in a given data set - ANSWER✔✔-sample
size
Copyright ©Stuvia International BV 2010-2024 Page 1/36
,Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
how does the variance equation change if you were calculating the variance within your sample alone
(and not for the population?) - ANSWER✔✔-you could divide by n instead of n-1
why do you need to square root the variance to get the standard deviation - ANSWER✔✔-the value lies
beyond the Y scale
How do we find if there is a relationship or correlation between certain variables - ANSWER✔✔-1. plot
the variable
2. calculate correlation coefficient
How do you calculate the correlation coefficient - ANSWER✔✔-1. center the data for both variables (xm-
xbar) x (ym-ybar)
2. calculate the "sum of products", add all units deviated sum scores
3. calculate the covariance by dividing this by n-1
4. calculate the correlation coefficient by dividing by the product of the two standard deviations
what is the range of values that the correlation coefficient includes? - ANSWER✔✔--1 to +1
How do we interpret correlation coefficients? - ANSWER✔✔-1. strength, The closer to 1 the stronger
2. directionality, - is negatively correlated, + is positively correlated
What are the benchmarks for weak, moderate, and strong relationships ? (according to Cohen) -
ANSWER✔✔-r>.1 = weak relationship
r>.3 = moderate relationship
r>.5= strong relationship
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,Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
what strength? r>.1 - ANSWER✔✔-weak relationship
what strength? r>.3 - ANSWER✔✔-moderate relationship
what strength? r>.5 - ANSWER✔✔-strong relationship
what are the univariate descriptive statistics - ANSWER✔✔-mean, sum of squares, variance, standard
deviation
what are the bivariate statistics - ANSWER✔✔-sum of products, covariance, correlation
what does univariate mean - ANSWER✔✔-a type of inferential statistics that consists of observations on
only a single variable
The main purpose of univariate analysis is to describe the data and find patterns that exist within it.
ex. finding mean, median, mode
what does bivariate mean - ANSWER✔✔-a type of inferential statistics that deals with the relationship
between two variables
what are parameters - ANSWER✔✔-a value that describes the population
what are estimates - ANSWER✔✔-a value that describes the sample
is 𝑥̅ a estimate or parameter - ANSWER✔✔-estimate, it describes a sample
Research questions are usually about... - ANSWER✔✔-the population
Copyright ©Stuvia International BV 2010-2024 Page 3/36
, Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024
what is Descriptive Statistics - ANSWER✔✔-statistics which summarize/describe properties of the sample
(or the population if we gather data from the entire population)
what is Inferential Statistics - ANSWER✔✔-statistics which draw conclusions/inferences regarding the
properties of the population, but based only on sample data
is 𝑥̅ a descriptive or inferential statistic - ANSWER✔✔-descriptive
if we compare 𝑥̅ to μ is it a descriptive or inferential statistic - ANSWER✔✔-inferential
How do you know which statistical analysis is important - ANSWER✔✔-Depends on
1. Study design/research question
2. Types of variables (level of measurements, distribution)
3, Whether assumptions of the analyses are met
What are variables - ANSWER✔✔-a characteristic that varies across observations
ex. age
are variables columns or rows in spreadsheets - ANSWER✔✔-columns
what is the independent variable - ANSWER✔✔-the variable the research is manipulating
ex. treatments
what is dependent variable - ANSWER✔✔-the variable we are measuring in response to the treatment
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