1. Square root of the Variance:
AP Stats
Chapter 6 Review
Standard Deviation
Square root of the Variance:
But use a calculator!!
STAT
CALC
1-VAR Stats
-or-
2nd STAT
MATH
stdDev(

2. Determines number of standard deviations from the mean:
AP Stats
Chapter 6 Review
Z - Scores
Determines number of standard deviations from the mean:

3. GOALS: move center (mean) to zero change units to standard deviations
AP Stats
Chapter 6 Review
Standardizing
GOALS: move center (mean) to zero
change units to standard deviations

4. Standardizing Shift Left/Right – ADD constant to everything EXCEPT
AP Stats
Chapter 6 Review
Standardizing
Shift Left/Right – ADD constant to everything
EXCEPT
spread: range, IQR, standard deviation

5. Changing Spread (units) – MULTIPLY EVERYTHING by constant!
AP Stats
Chapter 6 Review
Standardizing
Changing Spread (units) –
MULTIPLY EVERYTHING by constant!

6. Normal Model +/- 1 std.dev.
AP Stats
Chapter 6 Review
Normal Model +/- 1 std.dev.

7. Normal Model +/- 2 std. dev.
AP Stats
Chapter 6 Review
Normal Model +/- 2 std. dev.

8. Normal Model +/- 3 std.dev.
AP Stats
Chapter 6 Review
Normal Model +/- 3 std.dev.

9. Graphing a Normal Model TI-83
AP Stats
Chapter 6 Review
Graphing a Normal Model TI-83
Enter a formula in ‘y=‘
Defaults: mean=0, std.dev.=1
Turn all STAT PLOTS OFF
You will need to set the window to fix xmin, xmax, xscale.
ZOOM – 0 (zoomFit)

10. Z-Scores Percentiles TI-83
AP Stats
Chapter 6 Review
Z-Scores Percentiles TI-83
To find the percentage of data that fall below a given z-score*:
If min is , use –9999
If max is , use 9999
Defaults: mean=0, std.dev.=1
*you can also use the z-table

11. Z-Scores Percentiles TI-83
AP Stats
Chapter 6 Review
Z-Scores Percentiles TI-83
To find the z-score that cuts off a percentage of data*:
Defaults: mean=0, std.dev.=1
*you can also use the z-table

12. Z-Scores Percentiles TI-83
AP Stats
Chapter 6 Review
Z-Scores Percentiles TI-83
To SHADE the desired area given z-scores:
Be sure model has been graphed using ‘y=‘
Clear any previous shading by  2nd DRAW ClrDraw
Enter z-scores:
2nd DISTR
DRAW
If min is , use –9999
If max is , use 9999
Defaults: mean=0, std.dev.=1

13. Are You Normal? Is a normal model the best for your data?
AP Stats
Chapter 6 Review
Are You Normal?
Is a normal model the best for your data?
To find out, do a
Normal Probability Plot
Enter data into L1
Turn a STAT PLOT ON
Select the last ‘Type’ (looks like a line graph)
Select the correct Data List
Choose ‘Y’ for Data Axis
Specify the Mark you want (it doesn’t matter)
ZoomStat
The more ‘linear’, the more ‘normal’!