Statcrunch: learn.uakron.edu/statcrunch5.0 (no www. In front)
For this exercise you’ll utilize Statcrunch to calculate the appropriate confidence interval.
In addition you’ll decide which type of confidence interval is best for each situation. We’ve
discussed one sample, paired samples and independent samples. These choices correspond to
one sample, paired and two sample, respectively, in Statcrunch.
The data set you’ll use is located on my website: gozips.uakron.edu/~emr8. It is an
Excel file (“Data for confidence intervals”). Have both Statcrunch and this Excel file open at the
same time. Copy your data in Excel (using your favorite technique) and click in your statcrunch
window. In Statcrunch choose: Data-Load Data-From paste. In this window click the button
“paste data from clipboard”. Choose tab as the delimiter. Click Okay.
The menus you need are under Stat-T statistics- (you’ll decide which one you
need)- With data.
One sample or paired samples:
Select the variable(s) of interest and click Next. Click the button for confidence
interval and type your confidence level. Note that the confidence level is in proportion form.
Now click Calculate and a small window will open with your output.
2-sample interval
Uncheck the box for “pool variances”. In Sample 1 and Sample 2 fields you’ll select
the same variables. You’ll use the where fields to create the grouping. For example: To
compare study hours of Coke and Pepsi drinkers, in the first where fields you’ll type:
Cola_Pref=Coke. In the second you’ll type Cola_Pref=Pepsi. If you need to use a grouping
variable that is numeric, then you’ll type a number sentence: Age =19, Age<>19 (this notation
means not equal). Just remember to type everything exactly as it reads in the spreadsheet.
Click Next. In the next window select confidence interval and enter the appropriate
confidence level. Note that Statcrunch uses a proportion format rather than the percentage of
confidence. Click calculate and a small window will open with your output.