Twosided alternative hypothesis
The parameter is different from the null
value (it could be either smaller or
larger).
Type I error
Occurs if H0 is rejected when H0 is true.
Type II error
Occurs if H0 is not rejected when H0 is
STATS Page 4
Type II error
Occurs if H0 is not rejected when H0 is
false.
Does a parameter have a changing value or a fixed value?
Fixed, unchanging value
Do we know the parameter?
usually we do not know the parameter
because we cannot measure every unit
in the population
Three examples of what a parameter can be
1. A summary characteristic of a
population
2. A random situation
3. A comparison of different
populations
If we cannout find out the numerical value of a parameter,
how do we use it?
We use statistical methods to make a
good guess at the parameter
Define statistic, or sample statistic
a number computed from a sample of
values taken from a larger population
When is a sample estimate or estimate used?
when the statistic is used to estimate
the unknown value of a population
parameter
Can multiple samples of a population vary?
yes, the value of a sample statistic can
change from sample to sample
What is the procedure we use for making conclusions about
population parameters on the basis of sample statistics
Statistical inference
What is a confidence interval
an interval in which the researcher is
fairly sure will cover the true, unknown
value of the parameter, such as
"between 53% and 59%"
What is hypothesis testing used for?
to reject a hypothesis about a
population
Which notion do you want to reject when you are trying to
establish statistical significance?
You want to reject the hypothesis that
chance alone can explain the sample
results
What value is necessary in hypothesis testing, and what does
it mean if this value is true?
A null value is necessary, and if the null
value is true, it means that nothing of
interest is happening and that chance
alone can explain the sample results
What would the null value be for a weight loss clinic?
that the average weight loss for the
population of clinic patrons is 0. The
clinic wants to show that the actual
value is not zero, that average weight
less is greater than 0.
Two basic types of variables?
Categorical and quantitative
categorical  man, woman, dog, cat
quantitative, 10 pounds, 2 weeks
The big five scenarios for:
Population parameters
Categorical Variables
one population proportion = p
difference in two population
proportions = p
₁

p₂
Big Five scenarios
sample statisic
ne popula on p opo
on
o
p o a ility = p
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