Casio STAT 2 Manuel d'utilisateur télécharger pdf (Page 58)

The next step in the Chi-square calculation is the computation of the Chi-square

value:

where

E is the expected value, O is the observed value. The comparison chi-

square value must be found using a table of values based on degrees of freedom

and the confidence value. There are also many chi-square value calculators on

the Internet. The degrees of freedom are calculated by the number of rows minus

one times the number of columns minus one,

df = (R–1)(C–1). The degrees of

freedom value for this activity is four. If the confidence value is

p = 0.01, the

calculated chi-square value must at least 13.2767. The calculated chi-square value

is 11.043 which is only significant to the

p = 0.026. If the p = 0.01 parameter is

set, the student cannot reject the null hypothesis, therefore the candidate chosen

is independent of the class of the student.

Another example of when chi-square tests are used is when the results of a drug

are compared against the results of a placebo.

The students should be familiar with the following vocabulary:

Mean Standard deviation

Degrees of freedom Confidence

Population Sample

Chi-square test

Getting Started

For this activity you will need the Casio fx-9750G Plus graphing calculator

and the sample set of data. You may want the students to calculate these values

themselves and then check with the calculator.



= 

(E – O

)

Activity 11: Exit Polls Teaching Notes (continued)

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Casio STAT 2 Manuel d'utilisateur Page 58