Qim 511 spss chi square test
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QIM 511 SPSS : Chi-Square Test. Presented By : ang ling poh ong mei yean soo pei zhi. Nonparametric Techniques. Is used when having serious violations of distribution assumptions or not normal Appropriate for data measured on scales that are not interval or ratio.

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Qim 511 spss chi square test

QIM 511

SPSS: Chi-Square Test

Presented By:ang ling pohongmei yeansoopeizhi


Nonparametric techniques

Nonparametric Techniques

  • Is used when having serious violations of distribution assumptions or not normal

  • Appropriate for data measured on scales that are not interval or ratio.

  • Selection of nonparametric techniques are:

    • Chi-square tests

    • Mann-Whitney test

    • Wilcoxon signed-rank test

    • Kruskal-Wallis test

    • Friedman test

    • Spearman’s rank-order correlation


Chi square tests

Chi-square Tests

  • 2 Main types

  • 3 assumptions to deal before conducting chi-square tests:

    • Random sampling

    • Independence of observations

    • Size of expected frequencies


Chi square test for goodness of fit

Chi-square test for Goodness of Fit

  • used to compare observed and expected frequencies in each category.

  • sample size is usually small


Chi square test for goodness of fit1

Chi-square test for Goodness of Fit

  • Steps to conduct chi-square test for goodness of fit:

    • Select the Data menu

    • Click on Weight Cases to open the dialogue box

    • Click on the Weight cases by radio button

    • Select the relevant variable and move to Frequency Variable

    • Then, select Analyze menu

    • Click on Nonparametric Tests and then Chi Square

    • Select the required variable to move into Test Variable List box


Goodness of fit chi square output file will look like this

Goodness of fit chi square Output file will look like this:

  • You can see from the output that the chi-square value is no significant (p > .05).


Interpreting chi square test for goodness of fit

Interpreting Chi square test for Goodness of Fit

Example

Color preference of 150 people, p < 0.05


Presented by ang ling poh ong mei yean soo pei zhi

  • Chi-square requires that you use numerical values, not percentage or ratios.

  • Chi-square should not be calculated if the expected value in any category is less than 5.

Color preference of 150 people


Calculate chi square

Calculate chi-square

2 = Chi-square

O = Observed frequency

E = Expected frequency

k = number of categories, groupings, or possible outcomes


Calculate chi square1

Calculate chi-square

2 = 26.95


Calculate degrees of freedom df

Calculate Degrees of freedom (df)

  • Refers to the number of values that are free to vary after restriction has been placed on data.

  • Defined as N- 1, the number in the group minus one restriction.

df = N – 1

= 5 – 1

= 4


Critical 2 values

Critical 2 values

2 = 26.95 , df = 4 , p < 0.05

  • If chi-square value is bigger than critical value, reject null hypothesis.

  • If chi-square value is smaller than critical value, fail to reject null hypothesis.

Critical 2


Chi square test for relatedness or independence

Chi-square Test for Relatedness or Independence

  • Used to evaluate group differences when the test variable is nominal, dichotomous, ordinal, or grouped interval.

  • A test of the influence or impact that a subject’s value on one variable has on the same subject’s value for a second variable.


Chi square test for relatedness or independence1

Chi-square Test for Relatedness or Independence

  • Steps to conduct chi-square test for goodness of fit:

    • Select the Analyze menu

    • Click on Descriptive Statistics and then Crosstabs

    • Select a row and column variable to move into the respective box

    • Click on Statistics command pushbutton to open Crosstabs: Statistics subdialogue box

    • Click on the Chi-square check box then Continue

    • Click on the Cells subdialogue box

    • In the Counts box, click on the Observed and Expected check boxes

    • In the Percentages box, click on the Row, Column andTotal check boxes

    • Click on Continue and then OK.


Interpreting chi square test for relatedness or independence

Interpreting Chi square test for Relatedness or Independence

Example

Incidence of three types of malaria in three tropical regions.

H0 : The two categorical variables are independent.

H1. : The two categorical variables are related.


Calculate expected frequency

Calculate expected frequency

e = expected frequency

c = frequency for that column

r = frequency for that row

n = total number of subjects in study


Calculate expected frequency1

Calculate expected frequency

90 x 86

e =

250

= 30.96


Calculate chi square2

Calculate chi-square

2 = 125.516


Calculate degrees of freedom df1

Calculate Degrees of freedom (df)

df = (r-1)(c-1)

= (3-1)(3-1)

= (2)(2)

= 4

r = number of categories in the row variable

c = number of categories in the column variable


Find critical 2 values

Find critical 2 values

2 = 125.516 , df = 4 , p < 0.05

Critical 2

Chi-square value is bigger than critical chi-square value, reject null hypothesis.


References

REFERENCES

  • Green, S. B., Salkind, N. J., & Akey, T. M. (2000). Using SPSS for Windows: Analyzing and understanding data (2nd ed.). New Jersey: Prentice Hall.

  • Coakes, S. J., Steed, L., & Ong, C. (2010). SPSS:analysis without anguish: version 17.0 for Windows (Version 17.0 ed.). McDougall Street, Milton, Qld: John Wiley & Sons Australia, Ltd.

  • Hinkle, Wiersma, & Jurs. Chi-square test for goodness of fit. Retrieved from http://www.phy.ilstu.edu/slh/chi-square.pdf

  • Penn State Lehigh Valley. Chi-square test. Retrieved 9 March, 2011, from http://www2.lv.psu.edu/jxm57/irp/chisquar.html

  • Maben, A. F. Chi-square test. Retrieved from http://www.enviroliteracy.org/pdf/materials/1210.pdf

  • Bench, M. Interpreting the chi-square test. Retrieved 9 March, 2011, from http://www.mathbench.umd.edu/mod106_chisquare/page10.htm


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