Download AP Statistics TI 83/84 Calculator functions

AP Statistics TI 83/84 Calculator functions
Describing Data:
1. Stat-Edit: Put data into lists. You can highlight L1 or L2, etc in order to put a formula in for
that list. For example, in L2 you may write logL1.
2. Stat-SortA: Puts data from a list into ascending order. This is useful if you are trying find a
median, quartile or other percentile, or if you are making a stemplot.
3. 2nd-statplot: Contains all of the available graphs. Remember that the modified boxpot
automatically shows you the outliers.
4. zoom-9: zoomstat allows a plot to be displayed appropriately in the screen.
5. Stat-calc-1variable stats: Gives you all the important info about a set of data…mean, st dev,
5 number summary.
6. 2nd – list – math: This menu allows you to calculate many of the values found in one variable
stats.
Linear Regression:
1. Stat - calc - linreg(a + bx) – xlist - , - ylist - , – vars – yvars – function – Y1
This sequence creates a least-squares regression line for two quantitative variables and sends that
equation to Y1. This will also provide you with the correlation (r) and the coefficient of
determination (r2).
2. 2nd – statplot – Xlist: L1 – Ylist: 2nd-list-resid – zoom9: This sequence is for making a
residual plot. Reminder: a curved pattern in the residual (y – yhat) plot shows that a linear model
is not appropriate for representing the data.
Probability Simulations:
1. Math – PRB – randint(min, max, #values): example: randint(1, 400, 25) will give you 25
numbers randomly selected from the integers 1-400. This can be used for taking a sample.
Probability Calculations: (all found by hitting 2nd – distr)
1. normalcdf (min, max, mean, st dev): This will give you the area under the normal curve for a
given interval. This can be used to find the probability of selecting an individual from a
population with a certain value or range of values. It can also be used to calculate the probability
of obtaining a certain sample mean (if sigma is known) or sample proportion in reference to an
approximately normally distributed sampling distribution. Remember in this case that you have
to use the appropriate formula for standard deviation. It can also be used if you are using the
normal approximation for the binomial distribution.
Example: Heart rates are normally distributed with mean of 72 and a standard deviation of 8.
What is the probability of obtaining a random sample of 5 individuals with a mean heart rate of
less than 65? Ans: normalcdf(-1E99, 65, 72, 8/√5).
2. invNorm (%): gives you the z-score for a given percentile.
3. invNorm (%, mean, std dev): Gives you the raw data value which corresponds to a certain
percentile. Ex: What is the cut off point for the highest 2% of heart-rates?
Ans: invNorm(.98, 72, 8).
4. binompdf (n, p, X): Finds the probability of x number of successes in a binomial setting.
5. binomcdf (n, p, X): Finds the probability of x or fewer successes in a binomial setting.
Ex: The probability of randomly guessing correctly at a multiple choice question is .2. If Sally
guesses at all 20 questions, what is the probability that she will get at least 6 correct. Ans: 1 –
binomcdf (20, .2, 5).
6. geometpdf (p, X): In the geometric setting this gives you the probability of achieving the first
success on the xth trial.
7. geometcdf (p, X): In the geometric setting, this gives you the probability of achieving the first
success on x or fewer trials.
Inference:
1. Stat-Test: All of your tests and intervals are in this menu.
2. How to perform a chi-squared GOF test on the TI-83: Put observed counts in L1 and the
expected counts in L2. For L3, put in the formula (L1 – L2)2/L2. Use 2nd – list – math – sum in
order to find the sum of L3. Take that sum and put into the following in order to find the p-value.
χ2-cdf (sum, 1E99, df). df = # categories – 1.
Other Important Calculator Reminders:
1. When you perform a linear regression, r and r-squared should appear on the screen. If
you have reset your calculator or replaced the batteries, they may not appear. To get them
back, you must go to 2nd and catalog. This gives you an alphabetical listing of all functions.
Go to DiagnosticOn and hit enter twice.
2. If your lists get deleted, hit Stat – Edit – SetupEditor L1, L2, L3, L4, L5, L6 and enter.
All of your lists should be back.
3. When using calculator functions for probability (Normal, binom, geomet), make sure that
you label every part of the function you write down. You must write the numbers you used
for the calculation, but also what they represent.
Important things to memorize:
1. Interpret the meaning of the r-squared value.
_____% of the variation in the y-variable is accounted for by the least squares regression line
with the x-variable. (answer in context with the specific x and y variables)
2. Interpret the slope of the regression line.
As the x-variable increases by one unit, the y-variable increases by, on average, b units. Again,
the variables, units, and slope, must be in the context of the problem.
3. Interpret the 95% confidence level.
95% of all samples will yield an interval which contains the true population mean. (or proportion
if that relates to your problem)
4. Describe the distribution.
Use SOCS. Answer in context. Write a description, not a list.
For scatterplots: direction (+ or -), strength, form (linear?), outliers
5. Interpret the meaning of the p-value.
P-value is the probability of obtaining a sample mean/proportion (as large or larger/as small or
smaller/as extreme or more extreme….depending on Ha) than the one obtained from the sample,
if the null hypothesis is true.
6. Interpret the z-score.
Tells you how many standard deviations above/below (+/-) the mean a data value is.
7. Know how to set up every test/interval and how the conditions are satisfied for each one.
Feel free to offer suggestions for anything else you think should be included on this list.