Statistics Exam 1

represents number of standard deviations a data value falls above or below the mean.

• z= (X-μ)/σ
• X= score
• μ= mean
• σ= standard deviation

divides a distribution into 100 equal parts.

Percentile= [((# of values less than X) + .5)/total # of values] * 100%

extremely high or low value in a set of data

Bell-shaped

given to a normal (bell-shaped) distribution

• | | | | I | | | |
• [ 68%]
• [ 95% ]
• [ 99.7% ]

• First digit on one side, second digit(s) on the other side.
• ex.: 18 24 25 28 39 45 46 46 49

• 1 | 8
• 2 | 4 5 8
• 3 | 9
• 4 | 5 6 6 9

• No order
• ex: religion, race, hair color, gender

• low detail order
• ex: sequels, seasons, grades, months, alphabet

• High detail oorder, 0≠ nothing
• ex: temperature, clock time, years, IQ

• high detail order, 0= nothing
• ex: height, speed, salary, age

• -class
• -frequency
• -percent

• -class
• -class boundaries (the x.5 numbers above and below each class)
• -frequency
• -cumulative frequency (total up to a certain point; add number from the class before)

*list classes not listed or classes in between

• -class
• -class boundaries (x.5 above and below number)
• -frequency
• -cumulative frequency (add frequency from class before)
• -relative frequency (frequency÷total from cumulative frequency)
• -cumulative relative frequency

bar graph

line graph that originates from 0 before first value and ends at 0 after last value.

line graph that originates from 0 before first value and ends with a horizontal line after last value.

• mode
• median
• (symmetrical) mean; (skewed) median
• (symmetrical) mean; (skewed) median

bar graph used to show frequencies for nominal or qualitative variables.

line graph used to show a pattern or trend that occurs over a period of time. Doesn't originate from 0 and ends at last value.

used to show the relationship between the parts and the whole.

round to one more decimal place than occurs in the raw data.

average of highest and lowest value.

sum of (weights*values)÷sum of weights

the average of the squares of each value's distance from the mean. σ^2

• ex: (0+2+0+0+1+1+0)^2 ÷ 7
• σ^2= 6/7

the square root of the variance. σ

round to one more decimal place than occurs in raw data

while doing the mean, subtract 1 from the bottom number in the division.

• ex: 0+4+0+0+1+1+0 ÷ 7-1
• variance: s^2= 6/6= 1
• std. deviation: s= 1

• CVar= (σ ÷ μ) * 100%
• μ: mean
• σ: std. deviation

When comparing two variations, the higher number is more variable.