Lecture 4

Question 1

What are the 3 Central tendencies?

Answer 1

1.) Mean
2.) Median
3.) Mode

Question 2

Define Mode

Answer 2

The most frequent score (highest f value)

Question 3

Define Median

Answer 3

The 50th percentile (score above or below which half of all score falls)

Question 4

Define Mean

Answer 4

The average of all the values (sum of all scores in a distribution divided by the total # of scores)

Question 5

What are the steps to finding Mode?
- can there be more than one mode?
- how to find if grouped frequency?

Answer 5

Steps: 1.) rank data 2.) look @ score that is most frequent 3.) if grouped distribution (binned) look @ which has the largest f value (highest score in frequency column)
*no formula for finding mode
*can have more than one value for mode

Question 6

What is Bimodal Distribution? What is Trimodal Distribution?

Answer 6

Bimodal = 2 modes

Trimodal = 3 modes

Question 7

What are 3 disadvantages of Mode?

Answer 7

1.) Unstable = may change depending on methods for grouping
2.) Terminal Statistic = not useful from further calculations
3.) Ignores extreme scores

Question 8

What is Median?
- finding if N is odd vs if N is even?

Answer 8

The score @ 50th percentile that represents the typical/middle score & divides data in 2
* the exact middle score in the range if N is odd
* divides two scores if N is even

Question 9

What is Mean?
- what is it’s importance to central tendencies?

Answer 9

Mean is the average (sum of raw scores divided by the # if total scores) and is the most used index of central tendency & most sensitive
- mean is affected by every score in the distribution meaning outliers have a great effect on it

Question 10

What is Mean used for?

Answer 10

Used for subsequent calculations of statistical interference
*which is why it is importantly to recalculate every time a score is added/adjusted as the value changes every time a number is altered

Question 11

What is the Relationship among Mean, Median, & Mode?

Answer 11

When data is distributed normally, the 3 measures of central tendancy all fall @/near the same value
- when data are skewed these values are no longer identical

Question 12

Use mode if…

Answer 12

Only a rough estimate of central tendency is needed & the data are (nearly) normal

Question 13

Use median if…

Answer 13

Data are on an ordinal scale (ranked), middle score or most typical score of group is needed, or is the curve is badly skewed by extreme scores

Question 14

Use mean if…

Answer 14

The data is near normal & of the interval/ratio type or if further calculations, such as standard deviation or standard scores, are to be made