Ch. 5, 8, 11 Flashcards
The Percentile Point is at the….
Pth Percentile Rank
The Population Distribution involves the ?
Mean (mu) AND the Standard Deviation (sigma)
In a RANDOM sampling procedure, sample data are drawn from the ?
Population randomly & independently
The mean & the SD of the Sample Distribution are symbolized by:
X bar & s
Both the Population & Sample Distributions are distributions of:
RAW SCORES
Population Mean & Sample mean are …
Usually different from one another
Sampling Distribution is a distribution of :
SAMPLE MEANS
Mean of the Sample Means is symbolized by:
X bar & little x bar
Sample mean is assumed to be the same as
The Population Mean
The SD of the sampling distribution is called the:
Standard Error of the Mean (SE)
The Standard Error of the Mean is an index of
ERROR
The Standard Error of the Mean is estimated by:
the SD divided by the square root of N (sample size)
When the population SD is known the SE is computed by:
sigma (SD) divided by the square root of N (sample size)
When the population Standard Deviation is NOT known, the STANDARD ERROR is computed by:
s divided by the square root of N (sample size)
Distribution of the Sample means is called:
Sampling Distribution
How would you describe:
P.90 = 80
80 is at the 90th percentile rank
How many Quartile points are there?
there are 3;
Q1, Q2, Q3
what are the names of the quartile points & their percent’s ?
Lower Quartile is Q1 = 25
Middle Quartile is Q2 = 50
Upper Quartile is Q3 = 75
Interquartile Range is:
Q3 - Q1
P.75 - P.25
Semi Quartile Range is
Q3 - Q2 divided 2
P.75 - P.25 divided by 2
Z score is a measurement of
Relative Standing on the SD unit
Normal Distribution is
a theoretical distribution based on an Infinite # of cases
In a Normal Distribution the Mean, Median, & Mode are
ALL identical AND they divide the distribution into equal halves
ND is shaped how ?
ND is what about the central point?
ND is Bell shaped & Symmetrical about the central point
What is it called when the tails of the ND get closer to the x axis as they move AWAY from the Central point BUT never touch the x axis ?
Asymtotic to x-axis
SND stands for
Standard Normal Distribution
SND is a ND of
Standard Scores
A variety of distributions can be compared because all of them have the SAME
Mean: 0
SD (1.0)
the SND has the same WHAT as the ND?
the same shape
WHAT doesn’t change the SHAPE of the original distribution?
the Standardization aka z transformation doesn’t change
What is an OTHER standard score ?
standard score = bz + a
When you compare T-scores & Z-scores what do you find ?
T-scores don’t use negatives or decimals
We use a SAMPLE MEAN to
estimate the POPULATION MEAN
What does SRS stand for?
Simple.Random.Sampling
Name the 3 characteristics of SRS
- Random: all elements in population have equal chance of being selected
- Representative: Sample should represent ALL aspects of Population
- Independent: selection of ONE element does not have any influence on selection of other elements
Central Limit Theorem:
Sampling distribution:
- is normal when population distribution is Normal
- approaches a ND as sample size increases even if the population is NOT normal
Estimations of population parameters:
we use the sample mean to estimate the population mean
Point estimation:
uses a Sample mean to estimate the population mean; there is NO index of error
Interval estimation:
uses a score interval to estimate the population mean; there IS an INDEX of ERROR
this one is better than point estimation
