Lecture 1-4

Question 1

What do you have be to double-check when reading values in histogram and bar graphs(clustered, stacked, etc)?

Answer 1

If the values are row, column totals, or sample totals(n)

Question 2

What are charts that display bivariate relationships?

Answer 2

Panelled pie charts, panelled histograms, stacked/ clustered bar graphs,

Question 3

What characteristics do descriptive data focus on?

Answer 3

Centre pf data-main
Spread of data-average
Shape of data-ratio level variables only

Question 4

What characteristics do descriptive data focus on?

Answer 4

Centre pf data-median
Spread of data- mean average
Shape of data-ratio level variables only

Question 5

What does descriptive stats depend on?

Answer 5

Level of measurement for variables

Question 6

Descriptive stats- define and describe the difference between mode, median and mean

Answer 6

Mode: most common.
Median: the middle of the data. “50th percentile”
Mean: average of data.

Question 7

Which level of measurement is used for which description, and why?

Answer 7

4 leavels of measurement from least to most accurate:
Dictonomous: Mode
Nominal: Mode
Ordinal: Mode, Median
Ratio: Mode, Median, Mean
Ordinal variables: can’t do Mean because can’t apply mathmatical formula
Ratio: can do Mean beacuse can do math formula: total of values/ total of sample

Question 8

What does cell frequency mean?

Answer 8

“Hard counts” of a cell

Question 9

What does IAP mean?

Answer 9

Not applicable

Question 10

In frequency percentage, What is the difference between percent vs. valid percent vs. culumulative?

Answer 10

Valid percent excludes missing data.

Culumulative percent: culumulating previous valid percent and helps to find Median of data

Question 11

What is the equation for mean? What does each of the symbol mean?

Answer 11

Mean= Sigma X/ n

Question 12

How to find median in ordinal variables?

Answer 12

By stacking values in hierachy. culumulative percent. Cannot locate the exact value, but only rough

Question 13

What does measures of variation tell us about data? How is it different from central tendencies?

Answer 13

Measures of variation tell us - how spread out the data is. It is important because

Question 14

What is a range?

Answer 14

Range: difference b/w max and min

Question 15

What is the Inter-Quartile Range and why is it important?

Answer 15

-Distance between the 25th and 75th percentile, excluding the top and bottom 25 percentile
-Important because it is an effective way to avoid calculating “outliers” if there are a lot present

Question 16

What is the level of measurement data that range has the best use for?

Answer 16

Ratio level variables. Sometimes also ordinal if it has a large range.

Question 17

What is a boxplot?

Answer 17

In SPSS, a visual graph that displays the RANGE- median, minimum, maximum, IQR, and flags extreme values

Question 18

What is Standard Variation and why is it important?

Answer 18

• Standard Variation(SD) is a mathmatical formula calculating how spread out the data is.
• SD relies on histogram graph curve to show how spread out the data is
• SD is ONLY calculated for ratio level data.
• SD is compared in relation with the Mean, which has a value of 0
• SD values include +/-1,2,3

Question 19

What you must do when crafting a histogram?

Answer 19

Add the overlaying CURVE

Question 20

What is the equation for sample SD?

Answer 20

S = √∑ (X - M) 2 / n - 1

Question 21

What does Sigma mean?

Answer 21

culumative or sum of something

Question 22

What is a Normal Distribution on histogram and why is it important? What are the important characteristics of ND?

Answer 22

• A set of Data that has a symmetrical curve on a histogram
• Mean, median and mode should be roughly the same
• “unimodal”- one value of mode
• A lot of types of statstics need the Normal Distribution in order to be used.

Question 23

What are the Standard Deviations in a normal distribution?

Answer 23

• 68% with +-1 SDs
• 95% within +-2 SDs
• 99% within +-3 SDs

Question 24

How do you interpret and explain SD

Answer 24

i.e. 50% fall between +-1 SD AWAY from the mean

Question 25

What is a Z Score and what is the mathmatical formula calculation

Answer 25

Standard Deviation expressed in Units of whole number values
Value indicates how Far away from the Mean a particular “case” is
basically Positive/Negative Z score indicate if case is above or below Mean
Z =(Case Value - Mean)/ Standard Deviation Value

Question 26

Skewed Distrbution or “SKEW”

WHy does it happen?

Answer 26

• Data set has too many positive or negative Outliers “skew” the distribution
• Positive or negative outliers mean outliers that either have positive or negative Standard Deviation Value

Question 27

What is a Kurtosis? How is it different from SKEW?

What are the descriptive termsof Kurtosis?

Answer 27

Kurtosis shows on the Y axis of the histogram. Skew shows on the X axis.
In another words, How “Long/peaky or flat/plateaued” the shape is
-Long/peaky: Leptokurtic
-Flattened/Plataeued: Platylkurtic

-

Question 28

How are Standard Deviation and Z Scores different?

Answer 28

Essentially
Std. Dev measures the deviation Score of the WHOLE sample or population
Z score measures the deviation Score of a SPECIFIC data (like an individual)

Standard Deviation is a measurement that describes the Overall Shape of the Dataset. (fat, skinny, skewed, kurtosis), as opposed to a Specific data value.

Z score is a Unit of Measurement like the metric system. It is used to show a Specific Data Value’s standard deviation on the distribution curve.