STATCRUNCH — ESTIMATION
example 6.24, page 183 discusses CONFIDENCE intervals ... here is that example done in StatCrunch
after entering the data in column 1 (and I also
renamed the column to temperature), click on STAT
/ T STATISTICS / ONE SAMPLE / WITH DATA
then select temperature and click on NEXT (DO
NOT CLICK ON CALCULATE)
select CONFIDENCE INTERVAL (you can leave the LEVEL
at 0.95), then click on CALCULATE
1
STATCRUNCH — ESTIMATION
you should see the results on the
right ... they match the results in
Riosner but have a few more
decimal places
example 6.35 uses the same data, but says to
assume you have N=100, not N=10 ... you have
the MEAN, STANDARD DEVIATION, and N so
instead of selecting WITH DATA, select WITH
SUMMARY
fill in the values and click on NEXT
2
STATCRUNCH — ESTIMATION
select CONFIDENCE BAND and click on
CALCULATE
again, you see the same values as found in
Rosner (again, with more decimal places)
3
STATCRUNCH — ESTIMATION
table 6.5 on page 189 shows you data from a t‐distibution, from table 5 in
the appendix
you can also use StatCrunch to determine these values
start with STAT / CALCULATORS / T
NOTE: this allows you to get values for degrees of freedom that are not in
table 5 in Rosner
if you then enter 29 for DF and 0.975in the
box on the lower right and click on calculate,
you will see Prob(X<=2.0452297 )
the same number you see in Rosner
TRY THIS WITH THE OTHER DF IN THAT TABLE
(4 and 9) ‐‐‐ Rosner labels that column d, but
it really is DF for degrees of freedom
4
STATCRUNCH — ESTIMATION
example 6.49 calculates a confidence interval for a proportion using a normal approximation
you can also try StatCrunch to do this
select STAT / PROPORTIONS
/ ONE SAMPLE / WITH
SUMMARY
fill in the values and click on NEXT (NOT CALCULATE)
you can see N on page 206 and it is 10,000 ... since
P=0.04, the number of success was 400 (or you can
see those two numbers on page 205 in example 6.48
s
elect CONFIDENCE INTERVAL and make sure that the
METHOD says STANDARD‐WALD
that method uses a normal approximation to determine
the confidence interval
then click CALCULATE
5
STATCRUNCH — ESTIMATION
6
you will see the same
confidence interval that is
shown in Rosner
example 6.51 on page 208 asks for an EXACT CONFIDENCE INTERVAL and Rosner furst uses Table 7A in the
appendix, and then uses Excel
the tables in the appendix are a left over from pre‐computer days and NO ONE SHOULD EVER USE THOSE CURVES
to calculate EXACT limits ... you can (and SHOULD) use StatCrunch (more exact than the curves and a LOT easier
than the Excel method shown in Rosner)
do the same steps as the normal approximation (STAT / PROPORTIONS / ONE SAMPLE / WITH DATA, and then fill in
the number of SUCCESSES (2) and OBSERVATIONS (20) ... those numbers are in example 6.50 on page 207
HOWEVER, this time make sure that the METHOD says
AGRESTI‐COULI
that method is an EXACT method
then click CALCULATE
you will see results that are very close
to those shown in Rosner
try example 6.52, EXACT 99% (not
(95%) limits
make sure you change the 0.95 to 0,99
and also make sure you use the
AGRESTI‐COULI method
STATCRUNCH — ESTIMATION
example 6.40 shows percentiles from a ch‐square distribution found in table 6 in the appendix
you can also use StatCrunch
select STAT / CALCULATORS / CHI‐SQUARE
if you enter 10 for DF and then use the box on the lower right to fill in first 0.975 then 0.25, you will see the values
you see on page 199 in Rosner (make sure that the symbol after PROB is <=)
7
STATCRUNCH — ESTIMATION
example 6.41 calculates a confidence interval on a variance
you can do that in StatCrunch
select STAT / VARIANCE / ONE
SAMPLE / WITH SUMARY
fill in the values and click on NEXT
select CONFIDENCE INTERVAL then click on
CALCULATE
8
STATCRUNCH — ESTIMATION
the answer matches the values in ROSNER
NOTE: there is no calculator in StatCrunch for a
confidence interval on a standard deviation
however, as pointed out on page 201 in Rosner in
example 6.41, you can calculate a confidence interval
on a variance, then take the square root of the lower
and upper limits to get a band on the standard
deviation
9