What are the three measures of central tendency? Give a discription of each.
Mean, Median and Mode.
Mean: Average
Median: Middle number
Mode: Number most common
100
What is the formula for standard deviation of a population?
sum of (x-M)^2/N all under the square root
100
When is using zscores useful?
Let's us look at relative performance compared to other data points.
100
What does SEm stand for?
Standard Error of the mean
100
What does a normal curve look like?
Bell Shaped
200
What are the four scales of measurement?
Nominal
Ordinal
Interval
Ratio
200
What is the standard deviation of the following numbers:
0
2
6
10
12
4.56
200
What is the formula for finding the zscore
z= (x-m)/s
200
Define unbiased, biased and sampling.
Unbiased: The sample represents the population
Biased: The sample does not represent the population
Sampling: the process of taking a smaller group of participants/score from a larger population.
200
Draw a curve that is positively skewed.
Positive: tail ends to the right
300
What mean does the "M" stand for and what mean does "m" stand for?
"M" :Population (all of the people about whom a study is meant to generalize)
"m" :Sample (a subset of the population)
300
What does the standard deviation represent?
Indicates how well the mean describes the entire dataset.
300
What is the formula to convert zscores to rawscores?
x=z(s)+m
300
What is the formula sample SD?
S= sum of (x-m)^2/ (n-1) all under sqrt
300
What are the steps to get from a raw score to a percentile rank. (include formulas)
raw score ---- zscore ---- percentile rank
z=(x-m)/s requires z table
400
What kind of data can be used to calculate a median?
Ordinal, Interval, Ratio.
400
How many Standard Deviation units is 68% from the mean?
Given the following numbers 68% of the scores fall between what two numbers?
0
2
6
10
12
SD: 4.56
If m=6
1 Standard Deviation Unit
Between 1.44 and 10.56
400
Given the following information calculate the zscores and determine in which class this particular student is doing better in.
Biology: x=70 M=40 S=10
Spanish: x=70 M=50 S=5
Biology: 3
Spanish: 4 (better)
400
Given the following information find the 68% and 95%confidence interval.
m= 5.3
SEm= .72
68%: 4.58 - 6.02
95%: 3.86 - 6.74
400
Define zscore
A single datapoint in standard deviation units from the mean.
500
Why is STATISTICS and science so IMPORTANT?!
In order to show if the data is showing a pattern vs. data due to chance.
500
How many standard deviation units is 95% from the mean?
Given these numbers 95% of scores fall between what two numbers?
67
24
30
23
37
45
m=37.7
SD: 15.1
2 Standard Deviation Units
between 7.5 & 67.9
500
Find the percentile for the following information:
m=1735
x=1200
SD=150
.0002--- .02% percentile
500
DOUBLE JEOPARDY!
Using the formula for Sample SD find the SEm for the following infortmation:
5
7
6
6
8
m=6.4
S=1.14
1.14/sqrt 5 = .51
500
Give physical characteristics of a frequencey distribution.
higher: gaps, inverted bell shape
lower: bell shape, touching, etc