Standard Deviation (1 Viewer)

[SEAKING]

anyone know how to do this manually? my calculator doesn't have this function.

unless it does.. o_0?
sharp el-531VH

 

[PC]

If you're doing the General course, then you're not expected to find SD by hand. Invest in a calculator that does have a SD function. In my opinion, get a second hand graphic calculator from e-bay or somewhere. They really do make stats a breeze. Enter your data, and ALL your results are there.

Anyway ... SD by hand.

1. First of all construct a frequency distribution table as you normally would; columns are score (x), frequency (f) and the fx column.

2. Calculate the mean (m) as you would normally. ∑fx/∑x.

3. Make a new column, deviation (d). This is the difference from each score (x) from the mean (m). Use absolute values (i.e. make any negatives into positives).

4. Make a new column, deviation squared (d²). Just square the values you have just got in the d column.

5. Add the d² column values.

6. Divide this total by the total frequency (like finding the average - ∑d²)/∑f).

7. Find the square root.

This is the standard deviation!

See! Easy!

 

[Studentleader]

4. Make a new column, deviation squared (d²). Just square the values you have just got in the d column.

We call it variance at my school

Done it right though, I also recommend getting a good calculator because you will use ~1/2 an A4 page per question manually.

EDIT: http://www.sharpusa.com/files/cal_man_el531v.pdf

You can do standard deviations on your calculator exept I can't understand it (Ctrl+F "standard" on the above link.)

STATISTICAL CALCULATIONS
Press @ m 1 to select single-variable statistics
mode and @ m 2 to select two- variable statistics
mode. The following statistics can be obtained for each statistical
calculation (refer to the table below):
Single-variable statistical calculation (12)
Statistics of 1
Linear regression calculation (13)
Statistics of 1 and 2 and, in addition, estimate of y for a
given x (estimate y’) and estimate of x for a given y (estimate
x’)
x Mean of samples (x data)
sx Sample standard deviation (x data)
1 σx Population standard deviation (x data)
n Number of samples
Σx Sum of samples (x data)
Σx2 Sum of squares of samples (x data)
y Means of samples (y data)
sy Sample standard deviation (y data)
σy Population standard deviation (y data)
Σy Sum of samples (y data)
2 Σy2 Sum of squares of samples (y data)
Σxy Sum of products of samples (x, y)
r Correlation coefficient
a Coefficient of regression equation (y=a+bx)
b Coefficient of regression equation (y=a+bx)
Entered data are kept in memory until @ c or @
m 1 (2) are pressed. Before entering new data,
clear the memory contents.
[Data Entry]
Single-variable data
Data k
Data & frequency k (To enter multiples of the
same data)
Two-variable data
Data x & Data y k
Data x & Data y & frequency k (To enter
multiples of the same data x and y.)
[Data Correction]
Correction prior to pressing k:
Delete incorrect data with ª.
Correction after pressing k:
Press > to confirm the latest entry and press @
J to delete it.