Theory Section part 1.

Question 1

What is “Kurtosis”?

Answer 1

The kurtosis value provides information about the “Peakedness” of the distribution
Positive KS values indicate that the distribution is rather peaked (clustered in the centre), with long thin tails
Negative KS values indicate that the distribution is relatively flat (too many cases in the extremes)

Question 2

What is “Skewness”?

Answer 2

The Skewness value provides an indication of the symmetry of the distribution
If mean = median = mode, then it is a symmetric distribution

Question 3

What is “Standard Deviation”?

Answer 3

Is the square root of the variance

Question 4

What is “Variance”?

Answer 4

Variance of a set of observations is the average squared deviation of the data points from the mean

Question 5

What is “Simple Linear Regression”?

Answer 5

Technique used for determining how one variable of interest (the response variable) is affected by changes in another variable (the explanatory variable).

Question 6

What is “Correlation”?

Answer 6

Correlation describes the relationship between two continuous variables, in terms of both the strength of the relationship and the direction

Question 7

What is “Confidence Level”?

Answer 7

Det seier noko om kor sikre vi ynskjer å vere når vi generaliserer til populasjonen. Eit sikkerheitsnivå på 95% betyr at vi generaliserer i 95% av tilfella, men at vi tar feil i 5% av tilfella

Question 8

What is “Mode” (Typetal)?

Answer 8

The value that occurs most frequently

Døme: Det skonummeret det er flest av

Question 9

What is “Average” (Gjennomsnitt)?

Answer 9

The average of a set of observations

Døme: Alle skonummera lagt saman og delt på antallet

Question 10

What is “Median”?

Answer 10

An observation in the center of a data set (Halt of the data lies below, half lies above)
Døme: Det skonummret som er midt i rekkja av sko når dei er ordna frå minst til størst

Question 11

What is a Postive Skewness?

Answer 11

Positive SN values indicates clustering of scores at the low-end (left-handed side of the graph). Then the mean will be to the right of the median, median will be to the right of mode

Question 12

What is a Negative Skewness?

Answer 12

Negative SN values indicates a clustering of scores at the high-end (right-handed side of the graph). Then the mean will be to the left of median, median will be to the left of mode

Question 13

What is the formula for Skewness?

Answer 13

Dersom svaret > 1 er utvalet “Positively Skewed”/”Skewed to the right”
(Då er avstanden mellom XMAX og medianen større enn avstanden mellom XMIN og medianen)
Dersom svaret < 1 er utvalet “Negatively Skewed”/”Skewed to the left”
(Då er avstanden mellom XMax og medianen
mindre enn avstanden mellom XMin og medianen)

Question 14

Why do we use standard deviation instead of the variance?

Answer 14

Both variance and standard deviation measures the deviation of data points, but we need standard deviation compared to variance because it gives the value in the same unit as the observations

Question 15

What are the three main purposes of simple linear regression?

Answer 15

1. To describe the linear dependence of one variable on another
2. To predict values of one variable from values of another, for which more data are available
3. To correct for the linear dependence of one variable on another, in order to clarify other features of its variability

Question 16

What is an example of simple linear regression?

Answer 16

Imagine that your company wants to understand how past advertising expenditures have related to sales in order to make future decisions about advertising. The dependent variable in this instance is sales and the independent variable is advertising expenditures.

Question 17

What is the different types of kurtosis?

Answer 17

Leptokurtic (thin)
Mesokurtic (normal)
Platykurtic (flat)