STATISTIK INFERENSI: PENGUJIAN HIPOTESIS BAGI ANALISIS KORELASI ATAU HUBUNGAN (UJIAN – r ) Rohani Ahmad Tarmizi - EDU5950 1 STATISTIK INFERENSI ATAU PENTAKBIRAN (Inferential Statistics) Bertujuan untuk menerangkan ciri populasi berdasarkan data yang dikumpul daripada sampel. Tujuan ini berkait rapat dengan objektif kajian serta hipotesis atau soalan kajian. Membolehkan penyelidik membuat kesimpulan bahawa terdapat “statistik yang signifikan” atau “statistical significance” yang bermaksud boleh diterima pakai dengan meluas, meyakinkan. LANGKAH PENGUJIAN HIPOTESIS L1. Nyatakan hipotesis hipotesis statistik/sifar (H0) dan hipotesis penyelidikan (HA) – BERARAH ATAU TIDAK BERARAH L2. Tetapkan aras signifikan, taburan persampelan dan statistik pengujian yang akan digunakan – ARAS ALPHA = 0.01/ 0.05/ 0.10, TABURAN PERSAMPELAN z, t, F, r… STATISTIK PENGUJIAN (z, t, F, r…) L3. Tentukan nilai kritikal bagi taburan persampelan yang akan digunakan RUJUK JADUAL z, t, F, r… L4. Kirakan statistik pengujian (tests statistics) bagi taburan persampelan tersebut – RUJUK FORMULA L5. Buat keputusan, tafsiran, dan kesimpulan. L1. Nyatakan hipotesis Hipotesis penyelidikan – Terdapat perbezaan yang signifikan antara min tahap kepimpinan pengajaran Pengetua di Sekolah berprestasi tinggi berbanding dengan sekolah Swasta . Hipotesis nol/sifar – Tiada terdapat perbezaan yang signifikan antara min tahap kepimpinan pengajaran Pengetua di sekolah berprestasi tinggi berbanding dengan sekolah Swasta. 1. Nyata hipotesis nol dan penyelidikan. H O : µ 1 = µ2 HA : µ1 ≠ µ2 H O : µ1 ≥ µ 2 H A : µ 1 < µ2 H O : µ1 ≤ µ 2 H A : µ 1 > µ2 L1. Nyatakan hipotesis (dua kumpulan) Hipotesis penyelidikan – Terdapat perbezaan yang signifikan antara tahap kepimpinan pengajaran Pengetua, GPK2 dan GPK1. Hipotesis nol/sifar – Tiada terdapat perbezaan yang signifikan antara tahap kepimpinan pengajaran Pengetua, GPK2 dan GPK1. ANOVA’S Hypothesis H0: 1 = 2 = 3 = ... = c •All population means are equal •No treatment effect (NO variation in means among groups) H1: not all the k are equal •At least ONE population mean is different (Others may be the same!) •There is treatment effect Does NOT mean that all the means are different: 1 2 ... c UJIAN PERBANDINGAN MIN Ujian-t bebas (independent sample t-test) diguna untuk menguji hipotesis bahawa tiada/ada perbezaan min kemahiran IT antara kumpulan lelaki dan perempuan. Ujian-t bersandar (paired sample t-test) digunakan untuk menguji hipotesis bahawa tiada/ada perbezaan min tahap kepemimpinan mengarah dengan min tahap kepemimpinan partisipatif. Ujian analisis varians (analysis of variance, F test) digunakan untuk menguji hipotesis tiada/ada perbezaan min kepuasan bekerja antara kumpulan yang berbeza taraf pekerjaan. UJIAN PERBANDINGAN MIN-MIN Terdapat perbezaan min antara dua kumpulan yang dikaji (hipotesis penyelidikan) Tiada terdapat perbezaan min antara kumpulan yang dikaji (hipotesis sifar atau statistik). Disini yang dibanding adalah min ia itu skor pembolehubah bersandar daripada dua atau lebih daripada dua kumpulan yang dikaji. Uji diri anda!!!-Apakah pengujian statistik yang diperlukan, JIKA ANDA HENDAK? 1: Mengkaji sama ada terdapat perkaitan min kecekapan menjalankan penyelidikan dengan min pengetahuan statistik di kalangan pelajar Masters. 2: Menentukan sama ada terdapat hubungan antara tahap penglihatan “left field” dengan “right field” di kalangan pelajar. 3: Menguji terdapat hubungan antara kemahiran berkomunikasi dengan tahap keyakinan-diri dikalangan pelajar FPP. 4: Menguji terdapat hubungan kemahiran IT antara abang dan adik. 5. Mengenal pasti hubungan kecerdasan intelek dengan kecerdasan emosi BAGI TUJUAN SEDEMIKIAN!! ANALISIS KORELASI (Correlation Analysis) Analisis ini membolehkan penyelidik menguji hipotesis bahawa terdapat hubungan (relationship), korelasi (correlation) atau perkaitan (association) antara dua atau lebih pembolehubah Analisis ini bertujuan untuk menentukan hubungan/korelasi antara pembolehubahpembolehubah yang dikaji yang diperoleh/diukur daripada responden kajian iaitu kumpulan sampel ataupun populasi. Analisis ini digunakan untuk menjawab persoalan kajian seperti berikut: Adakah terdapat hubungan antara dua pembolehubah tersebut? “Is there relationship between the two variables?” Sejauh manakah hubungan tersebut? “How strong is the relationship?” Apakah arah hubungan tersebut? “What is the direction of the relationship?” ANALISIS KORELASI Analisis korelasi juga boleh dilanjutkan menjadi beberapa pembolehubah – MULTICORELATIONAL ANALYSIS Ia mengukur sejauh manakah dua atau lebih pembolehubah berubah (covary) secara serentak ataupun bersama-sama. It is a measure of how variables covary together, hence the word CORRELATION ANALISIS KORELASI Analisis juga membabitkan dua kategori pembolehubah iaitu pembolehubah prediktif dan pembolehubah kriterion. P/U prediktif adalah yang memberi kesan atau mempengaruhi P/U yang kedua. P/U kriterion adalah yang menerima kesan atau pengaruh daripada P/U pertama. X (prediktif) Y (kriterion) X1, X2, X3,.. Y (kriterion) Walau bagaimanapun, analisis ini hanya memeri gambaran hubungan dan tidak memberi rumusan “cause-and-effect relationship”. Sebagai contoh, penyelidik hendak menentukan hubungan antara: minat terhadap bidang dengan prestasi, pendapatan dan kepuasan bekerja kadar baja dan pertumbuhan pokok frekuensi merokok dengan frekuensi mendapat serangan jantung Umur dengan kadar ingatan jam mentelaah, amalan pemakanan, IQ dengan prestasi. Other Examples of Correlation Analysis A researcher interested in the relationship between measures of depression and violence among fathers. Relationship between age in years and performance in motor skills. Relationship between hours of leisure and performance in course. Specific Example For seven random summer days, a person recorded the temperature and their water consumption, during a three-hour period spent outside. Temperature (F) Water Consumption (ounces) 75 83 85 85 92 97 99 16 20 25 27 32 48 48 How would you describe the graph? Other Direction of Correlation Correlation A relationship between two variables. Explanatory (Independent) Variable x Hours of Training Shoe Size Cigarettes smoked per day Score on MUET Height y Response (Dependent) Variable Number of Accidents Height Lung Capacity Grade Point Average IQ What type of relationship exists between the two variables and is the correlation significant? Dua Cara Menentukan Korelasi Secara bergambar iaitu dinamakan gambarajah sebaran (scatter diagram) yang menunjukkan pola kedudukan pasangan titik-titik. Daripada gambarajah sebaran kita dapat merumus keteguhan (magnitud) korelasi tersebut serta arah korelasinya. Dua Cara Menentukan Korelasi Secara berangka iaitu dengan menentukan pekali, koefisi atau indeks. Daripada pekali tersebut kita dapat mengetahui keteguhan (magnitud) korelasi tersebut serta arahnya sama positif atau negatif. MEMBINA GAMBAR RAJAH SEBARAN Lakarkan dua paksi mengufuk dan mencancang Letakkan p/u X (IV or predictive) pada paksi mengufuk dan tandakan paksi tersebut Letakkan p/u Y (DV or criterion) pada paksi mencancang. Plotkan titik-kedudukan bagi setiap pasangan skor di lakaran tersebut ia itu titik persilangan titik bagi X dan titik bagi Y bagi setiap pasangan skor. Pola Kedudukan Titik Serta Garis Lurus Yang Terbentuk Menggambarkan Korelasi Atau Hubungan Iaitu: titik-titik yang terletak di atas garis lurus yang mendongak menunjukkan korelasi sempurna dan positif. titik-titik yang terletak di atas garis lurus yang menunduk menunjukkan korelasi sempurna dan negatif. titik-titik yang bersepah tanpa pola garis lurus menunjukkan tiada korelasi. Pola Kedudukan Titik Serta Garis Lurus Yang Terbentuk Menggambarkan Korelasi Atau Hubungan Iaitu: titik-titik yang menghampir dengan garis lurus yang mendongak menunjukkan korelasi teguh dan positif. titik-titik yang berjauhan daripada garis lurus serta juga mendongak menunjukkan korelasi lemah dan positif. Pola Kedudukan Titik Serta Garis Lurus Yang Terbentuk Menggambarkan Korelasi Atau Hubungan Iaitu: titik-titik yang menghampiri dengan garis lurus yang menunduk menunjukkan korelasi teguh dan negatif. titik-titik yang berjauhan daripada garis lurus yang juga menunduk menunjukkan korelasi lemah dan negatif. Scatter Plots and Types of Correlation x = SAT score y = GPA GPA 4.00 3.75 3.50 3.25 3.00 2.75 2.50 2.25 2.00 1.75 1.50 300 350 400 450 500 550 600 650 700 750 800 Math SAT Positive Correlation as x increases y increases Scatter Plots and Types of Correlation x = hours of training y = number of accidents Accidents 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 18 Hours of Training Negative Correlation as x increases, y decreases 20 x Absences x 8 2 5 12 15 9 6 Final Grade Grade 95 90 85 80 75 70 65 60 55 50 45 40 0 2 4 6 8 10 12 Absences y 78 92 90 58 43 74 81 14 16 x IQ Scatter Plots and Types of Correlation x = height y = IQ 160 150 140 130 120 110 100 90 80 60 64 68 72 76 Height No linear correlation 80 Displays of scores in a Scatterplot Hours of Internet Depression use scores per week from 15-45 Laura Chad Patricia Bill Mary Todd Angela David Maxine John Mean Score 17 13 5 9 5 15 7 6 2 18 10 30 41 18 20 25 44 20 30 17 48 29.3 Depression scores Y=D.V. 50 - 40 30 + M 20 + 10 M 5 - 10 15 20 Hours of Internet Use X=I.V. Association Between Two Scores Linear and non-linear patterns A. Positive Linear (r=+.75)B. Negative Linear (r=-.68) C. No Correlation (r=.00) Linear and non-linear patterns D. Curvilinear E. Curvilinear F. Curvilinear Analisis Korelasi Menunjukkan 3 perkara penting, iaitu: Arah/Direction (positive or negative) Bentuk/Form (linear or non-linear) Kekuatan/Magnitude (size of coefficient) PEKALI ATAU KOEFISI KORELASI TERDAPAT BEBERAPA JENIS PEKALI KORELASI IAITU: Pearson product-moment correlation Digunakan apabila p/u x dan y adalah pada skala sela atau nisbah atau gabungan kedua-duanya. Spearman rho correlation Digunakan apabila p/u x dan y adalah pada skala ordinal atau gabungan ordinal dengan sela/nisbah. Point-biserial correlation Digunakan apabila p/u x adalah dikotomus dan p/u y adalah pada skala sela atau nisbah. Pekali Pearson r = n [xy] - [xy] [ n x2 - ( x) 2 ] [ n y2 - ( y) 2 ] n = bilangan pasangan skor x y = jumlah skor x didarab dengan skor y x = jumlah skor x y = jumlah skor y Pekali Spearman r = 1 - [6B2] n [ n2 - 1 ] n = bilangan pasangan skor B = jumlah beza pasangan setiap skor Pekali Point-biserial r = y1 – y2 [ n1 n2 ] sy n[n-1] Interpreting Value of the Correlation Coefficient The coefficient vary from zero to one. Zero means there is simply no correlation between the two variables. One means a perfect correlation. Values approaching one is considered highly correlated. Values approaching zero is least correlated. A middle score indicates moderate or average correlation. Interpreting Positive Correlation A correlation can either be positively or negatively correlated. Positive correlation is indicated by a positive value is obtained. This means that the two variables are varying from each other: as X increases Y will also increase. Y being the criterion variables (dependent variables) and X the predictive variables (independent variables) Non-linear associations statistics Spearman rho (rs) - correlation coefficient for nonlinear ordinal data Point-biserial - used to correlate continuous interval data with a dichotomous variable Phi-coefficient - used to determine the degree of association when both variable measures are dichotomous Association Between Two Scores Degree and strength of association .20–.35: When correlations range from .20 to .35, there is only a slight relationship .35–.65: When correlations are above .35, they are useful for limited prediction. .66–.85: When correlations fall into this range, good prediction can result from one variable to the other. Coefficients in this range would be considered very good. .86 and above: Correlations in this range are typically achieved for studies of construct validity or test-retest reliability. Interpreting Value of the Correlation Coefficient The coefficient vary from zero to one. Zero means there is simply no correlation between the two variables. One means a perfect correlation. Values approaching one is considered highly correlated. Values approaching zero is least correlated. A middle score indicates moderate or average correlation. Guildford Rule of Thumb r Strength of Relationship < 0.2 Negligible Relationship 0.2 – 0.4 Low Relationship 0.4 – 0.7 Moderate Relationship 0.7 – 0.9 High Relationship > 0.9 Very high Relationship Other Strengths of AssociationBy Johnson and Nelson (1986) r-value Interpretation 0.00 No relationship 0.01-0.19 Low relationship 0.20-0.49 Slightly Moderate relationship 0.50-0.69 Moderate relationship 0.70-0.99 Strong relationship 1.00 Perfect relationship TYPES OF CORRELATION Pearson correlation coefficient. Spearman’s rank correlation coefficient. Point-biserial correlation coefficient. L1. Nyatakan hipotesis Hipotesis penyelidikan – Terdapat hubungan yang signifikan antara tahap kepimpinan pengajaran Pengetua dengan prestasi akademik sekolah di Sabah Hipotesis nol/sifar – Tiada terdapat hubungan yang signifikan antara tahap kepimpinan pengajaran Pengetua dengan prestasi akademik sekolah di Sabah L2. TETAPKAN ARAS ALPHA = 0.01/ 0.05/ 0.10, TABURAN PERSAMPELAN, STATISTIK PENGUJIAN Nilai alpha ditetapkan oleh penyelidik. Ia merupakan nilai penetapan bahawa penyelidik akan menerima sebarang ralat semasa membuat keputusan pengujian hipotesis tersebut. Ralat yang sekecil-kecilnya ialah 0.01 (1%), 0.05 (5%) atau 0.10(10%). Nilai ini juga dipanggil nilai signifikan, aras signifikan, atau aras alpha. L2. Taburan Persampelan Taburan yang bersesuaian dengan analisis yang dijalankan. Ia merupakan model taburan korelasi yang mana nilai korelasi itu bertabur secara normal. Di kawasan kritikal terletak nilai korelasi yang “luar biasa” -> Ha adalah benar Dikawasan tak kritikal terletak nilai korelasi yang “biasa” -> Ho adalah benar L3. Nilai Kritikal Nilai kritikal adalah nilai yang menjadi sempadan bagi kawasan Ho benar dan Hp benar. Nilai ini merupakan nilai dimana penyelidik meletakkan penetapan sama ada cukup bukti untuk menolak Ho (maka boleh menerima Hp) ataupun tidak cukup bukti menolak Ho (menerima Ho). Nilai ini bergantung kepada nilai alpha dan arah pengujian hipotesis yang dilakukan. L4. Nilai Statistik Pengujian Ini adalah nilai yang dikira dan dijadikan bukti sama ada hipotesis sifar benar atau salah. Jika nilai statistik pengujian masuk dalam kawasan kritikal maka Ho adalah salah, ditolak dan Hp diterima Jika nilai statistik pengujian masuk dalam kawasan tak kritikal maka Ho adalah benar, maka terima Ho. L4. Nilai Statistik Pengujian r uji = r uji = 6 d 1 n n2 1 2 L5. Membuat Keputusan, Tafsiran, dan Kesimpulan Jika nilai statistik pengujian masuk dalam kawasan tak kritikal maka Ho adalah benar, maka terima Ho. L5. Membuat Keputusan, Kesimpulan dan Tafsiran Jika nilai statistik pengujian masuk dalam kawasan kritikal maka Ho adalah tak benar, maka Ho ditolak dan seterusnya, Hp diterima (bermakna ada bukti Hp adalah benar) Correlation Coefficient - A measure of the strength and direction of a linear relationship between two variables The range of r is from -1 to 1. -1 If r is close to -1 there is a strong negative correlation 0 If r is close to 0 there is no linear correlation 1 If r is close to 1 there is a strong positive correlation Purpose – Determine relationship between two metric variables Requirement : DV - Interval / Ratio scale and IV- Interval / ratio scale Descriptive : Magnitude and Direction of Correlation, r Inferential: Hypothesis testing Hypotheses: HO: ρp= 0 HA: ρp≠ 0 HO: ρp= 0 ρp> 0 HO: ρp= 0 ρp< 0 Objektif kajian Mengkaji sama ada terdapat perkaitan bilangan ponteng kelas dengan prestasi dalam ujian. Soalan kajian Apakah perkaitan antara bilangan ponteng kelas dengan prestasi dalam ujian Hipotesis kajian Ho : Tiada terdapat hubungan antara bilangan ponteng kelas dengan prestasi dalam ujian HA : Terdapat hubungan antara bilangan ponteng kelas dengan prestasi dalam ujian Application 1 Absences Grade x 8 2 5 12 15 9 6 y 78 92 90 58 43 74 81 Absences x 8 2 5 12 15 9 6 Final Grade Grade 95 90 85 80 75 70 65 60 55 50 45 40 0 2 4 6 8 10 12 Absences y 78 92 90 58 43 74 81 14 16 x Pearson Correlation rp = n [xy] - [xy] [ n x2 - ( x) 2 ] [ n y2 - ( y) 2 ] n = no of pairs x y = summation of x multiply by y x = summation of x y = summation of y Computation of r 1 2 3 4 5 6 7 x y xy x2 y2 8 2 5 12 15 9 6 78 92 90 58 43 74 81 624 184 450 696 645 666 486 64 4 25 144 225 81 36 6084 8464 8100 3364 1849 5476 6561 3751 579 39898 57 516 r 3155 804 13030 = - 0.975 Inferential Analysis – Hypothesis Testing Steps in Hypothesis Testing 1. State the null and alternative hypothesis HO: ρp= 0 HA: ρp≠ 0 or ρp> 0 or ρp< 0 2. Determine critical value df = n – 2 One-tailed or Two-tailed 3. Calculate the test statistic 4. Make your decision 5. Make conclusion Reject H : Significant relationship between the two variables Fail to Reject Ho: No significant relationship between the two variables O Example 1 : Data were collected from a randomly selected sample to determine relationship between average assignment scores and test scores in statistics. Distribution for the data is presented in the table below. Assuming the data are normally distributed. 1. Calculated an appropriate correlation Data set: coefficient. 2. Describe the nature of relationship between the two variable. 3. Test the hypothesis on the relationship at 0.01 level of significance. Assign 8.5 6 9 10 8 7 5 6 7.5 5 Test 88 66 94 98 87 72 45 63 85 77 Pearson Correlation rp = 10 [ 5795.5 ] - [ 72 x775 ] [ 10 (544.5) - (72) 2 ] [ 10 (62441)- (775) 2 ] r = 0.8649 Inferential Analysis – Hypothesis Testing Steps in Hypothesis Testing 1. State the null and alternative hypothesis HO: ρ p = 0, HA: ρ p ≠ 0 2. Calculate the test statistic: 3. Determine critical value: df = n – 2, Two-tailed . 4. Make your decision: 5. Make conclusion: Calculate the test statistic X Y XY X2 Y2 8.5 88 748 72.25 7744 6 66 396 36 4356 9 94 846 81 8836 10 98 980 100 9604 8 87 696 64 7569 7 72 504 49 5184 5 45 225 25 2025 6 63 378 36 3969 7.5 85 637.5 56.25 7225 5 77 385 25 5929 Steps in Hypothesis Testing 1. State the null and alternative hypothesis HO: ρ p = 0, HA: ρ p ≠ 0 2. Calculate the test statistics: r = .865 3. Determine critical value: df = n – 2, Two-tailed. r critical= 0.765 4. Make your decision: r cal > r critical so reject null hypothesis, accept alternative hypothesis 5. Make conclusion: There is significant relationship between assignment scores and test scores r (8) = 0.87, p<0.01 Example 2 : A clinical psychologist hypothesizes a correlation between a personality dimension (Extroversion/introversion) and depression. Two questionnaires are administered. One measures the personality trait, with bigger scores indicating more extroversion and lower scores tending toward introversion. The other measures depression, with bigger scores reflecting greater depression. Lower scores on the depression inventory are not indicative of depression. 1. Calculated and describe the appropriate correlation coefficient. 3. Test the hypothesis on the relationship at 0.05 level of significance. Calculate the test statistic X Y X2 XY Y2 8 6 9 6.5 4 3.5 52 24 31.5 64 36 81 42.25 16 12.25 10 2 4 3.5 6 7.5 35 12 30 100 4 16 12.25 36 56.25 5 6 7 4.5 2 2.5 22.5 12 17.5 25 36 49 20.25 4 6.25 3 60 5 45 15 251.5 9 420 25 230.5 Steps in Hypothesis Testing 1. State the null and alternative hypothesis HO: ρ p = 0, HA: ρ p ≠ 0 2. Calculate the test statistic: r = -0.451 3. Determine critical value: df = n – 2, Two-tailed. r critical = 0.67 4. Make your decision: r cal < r critical so reject null hypothesis accept alternative hypothesis. 5. Make conclusion: There is no significant relationship between extroversion and depression measurement, r (8) = - .45 , p>0.05. Therefore we cannot conclude that those people who are extroverts are more likely to be depressed, whilst those people who are introverts are more likely not depressed. Spearman’s rank correlation coefficient Non parametric method: Less power but more robust. Does not assume normal distribution. The correlation coefficient also varies between -1 and 1 Purpose – Determine relationship between two rank scores Requirement : variables measured at ordinal scale and ordinal scale, ordinal scale and interval scale, ordinal scale and ratio scale Descriptive Direction Correlation Coefficient, Inferential r Hypotheses: HO: ρs = 0 HA: ρs ≠ 0 ρs > 0 ρs < 0 Strength / Magnitude Spearman rho Correlation r = 1 - [6D2] n [ n2 - 1 ] 6 d 1 2 n n 1 2 n = no of pairs D = summation of the differences between pairs of scores As a measure of popularity, the classroom teacher is asked to rank all of the children from the most to least popular. To measure dominance, the children are given the opportunity to play a new video game, but they must come to an agreement about which of them will go first, which will go second, and so on. The order which the children play the game is taken as the dominance hierarchy. A rank of 1 on Dominance is assigned to the most dominant child and A rank of 1is assigned to the most on popular child. 1. Calculate the appropriate correlation coefficient 2. Describe the nature of relationship between the two variables 3. Test the hypothesis on the relationship at 0.05 level of significance Example for Spearman rho Dominance X 1 Popularity Y 1 7 6 8 3 4 8 9 5 3 3 5 10 4 6 9 2 7 10 D D2 0 -1 -3 3 0 1 1 4 2 -8 0 1 9 9 0 1 1 16 4 64 r = 1 - [6D2] n [ n2 - 1 ] r = r 1 - [ 6(105 )] 630 10 [ 100 - 1 ] 990 = 1 – 0.642 r = 0.36 2. There is a positive and weak relationship between dominance and popularity. 3. Test the hypothesis on the relationship between the two variable at 0.05 level of significance. a. State the null and alternative hypotheses H O : ρs = 0 H A : ρs ≠ 0 b. rs = 0.36 c. Determine critical value Critical rs = 0.648 d. Decision: Since calculated rs (0.36) is smaller than critical rs (0.648.), fail to reject the null hypothesis, accept null hypothesis. e. Conclusion Conclude there is no significant relationship between dominance and popularity at 0.05 level of significance, rs =0.36, p> .05. Results showed that the more popular the child does not mean he or she is more likely to assume a dominant position in the class. Example2: Data solicited from a randomly selected sample were used to measure relationship between working environment and work commitment. EDA revealed the work commitment data did not meet the assumption of normality. 1. Calculate and describe the appropriate correlation coefficient 3. Test the hypothesis on the relationship at 0.05 level of significance ID 1 2 3 4 5 6 7 8 9 10 11 12 X 6 5 8 4 9 6 7 5 4 7 6 7 Y 15 34 11 9 17 12 13 23 11 12 14 16 r = 1 - [ 6 (242.5)] 12 [ 144 - 1 ] 1455 1716 r = 0.1521 r2 = COEFFICIENT OF DETERMINATION – TELL YOU HOW MUCH VARIATION OF Y IS EXPLAINED BY X X –WORK ENV Y-WORK COMM 6 15 5 34 8 11 4 9 9 17 6 12 7 13 5 23 4 11 7 12 6 14 7 16 Pangkat untuk X Pangkat untuk Y 6 D D2 8 -2 4 3.5 12 -8.5 72.25 11 2.5 8.5 72.25 1.5 1 0.5 0.25 12 10 2 4 6 4.5 1.5 2.25 9 6 3 9 3.5 11 -7.5 56.25 1.5 2.5 -1.0 1 9 4.5 4.5 20.25 6 7 -1.0 1 9 9 0 0 242.5 3. Test the hypothesis on the relationship between the two variable at 0.05 level of significance. a. State the null and alternative hypotheses H O : ρs = 0 H A : ρs ≠ 0 b. rs = 0. 587 c. Determine critical value Critical rs = 0.887 d. Decision: Since calculated rs (0.887 is larger than critical rs (0.587.), we reject the null hypothesis, accept alternative hypothesis. e. Conclusion Conclude there ino significant relationship between perception towards work environment with level of work commitment at 0.05 level of significance, rs =0.36, p< .05. Results showed that the positive and high perception on work environment has positive impact on work commitment of employees. Uji diri anda!!!-Apakah pengujian statistik yang diperlukan dan seterusnya jalankan analisis yang diperlukan EXAMPLE DATA Parents Marital Children Marital Performance Satisfaction Satisfaction Subject 1 1 3 70 2 3 2 80 3 7 6 40 4 9 7 35 5 8 8 50 6 4 6 40 7 5 3 30 Subjek Pangkat Agresif Pangkat Agresif 1 8 14 2 10 12 3 4 9 4 1 4 5 5 11 6 6 10 7 3 1 8 9 12 9 7 10 10 2 4 CONTOH DATA 3 Jantina Tahap Stail Kepemimpinan Kepimpinan Persepsi Prestasi oleh Guru 1 18 Autokratik 20 1 20 Autokratik 30 1 24 Autokratik 40 1 11 Demokratik 85 1 15 Demokratik 70 2 16 Demokratik 30 2 12 Demokratik 80 2 19 Autokratik 40 2 17 Demokratik 25 2 22 Autokratik 75 Point-biserial Correlation Purpose – Determine relationship between A DICHOTOMOUS VARIABLE (2 categories) and a continuous variable (interval/ratio data) Requirement : normally distributed continuous variables and independent variable with only two categories (ex: male/female, high/low, yes/no, part-time/full-time) r = • • • • • • y1 – y2 [ n1 n2 ] sy n[n-1] Mean of group 1 Mean of group 2 Std dev of continuous variable No of subjects in group 1 No of subjects in group 2 Total no of subjects Example1: A psychologist hypothesizes an association between marital status and need for achievement. A questionnaire measuring need for achievement is administered to married and single people. 1. Calculate the appropriate correlation coefficient 2. Describe the nature of relationship between the two variables. 3. Test the hypothesis on the relationship at 0.05 level of significance Marital status 2 2 1 1 1 2 1 2 2 1 1 2 1 1 Need for Achievement 3 7 12 16 24 11 15 10 11 18 22 9 19 17 Point-biserial Correlation r = • • • • • • y1 – y2 [ n1 n2 ] sy n[n-1] Mean of married subject = 8.5 (group 2) Mean of single subjects = 17.9 (group 1) Std dev of need of achievement scores = 5.89 No of married subjects = 6 No of single subjects = 8 Total no of subjects = 14 Calculate the test statistic y y 2 3 9 7 49 12 144 16 256 24 576 11 121 15 225 10 100 11 121 18 324 22 484 9 81 19 361 17 289 194 3140 S = y2 - (y) 2/ n n-1 S = 3140 - 1942 / 14 13 S = 5.8947 Point-biserial Correlation r = 17.9 – 8.5 5.89 r pb = (1.595) (0.514) r pb = 0.82 [8x6] 14 [ 14 - 1 ] The mean need for achievement for single individual is 17.9 and for married individuals is 8.5. There is a strong relationship between marital status and need for achievement with correlation coefficient of 0.82. Need of achievement for single individual is higher than married individual. 3. Test the hypothesis on the relationship between the two variable at 0.05 level of significance. a. State the null and alternative hypotheses HO : ρ pb = 0 HA : ρ pb ≠ 0 b. r pb = 0.82 c. Determine critical value Critical r pb = 0.532 d. Decision Since calculated r pb (0.82) is greater than critical r pb (0.532), reject the null hypothesis thus accept alternative hypothesis. e. Conclusion Conclude there is significant relationship between marital status and need for achievement, r pb (12)=.82, p<0.05 Findings indicated that single individuals showed a higher need for achievement compared to married individuals.
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