Research skills Quant Flashcards

Question

4 graphical descriptions of data

Answer 1

Bar chart - used to summarise categorical data Separate bars as unrelated categories Line chart - chart joining continuous data points in a single line Histograms - type of bar chart for continuous variables Bars joined, space shows no score in interval Box analysis - exploratory data chart showing median, central spread of data and position of relative extremes

Answer 2

Range - distance between lowest and highest score in sample - sensitive to outliers Interquartile range - distance between the upper and lower quartile in set of data Semi interquartile range - half of the interquartile range + not affected by outliers + better then range, focusing on central units - inaccurate with large class intervals Standard deviation - estimate of the average deviation from scores from the mean Indicator of how closely scores are clustered around the mean + most robust measure of dispersion - sensitive to extreme values

Answer 3

Corrected - used to estimate population standard deviation Uncorrected - used when not using the standard deviation to make estimates of the underlying population

Answer 4

Peak in middle Bell shaped curve Tails off symmetrically at either side of peak Generally more scores plotted, more like normal distribution becomes

Answer 5

Positive - peak shifted to left, tail towards right Negative - peak shifted to right, tail towards left

Answer 6

Bi modal - 2 peaks in distribution Multi modal - >2 major peaks in distribution

Answer 7

Kurtosis - measure of peak and flatness or steep and shallowness Leptokurtic - higher kurtosis/very peaked distribution Platykurtic - lower kurtosis/flat distribution Mesokurtic - between two extremes of peak and flatness

Answer 8

Distribution of z scores

Answer 9

how many standard deviations above or below a mean score is Subtract the sample mean from the score Then divide by the sample standard deviation

Answer 10

Sample mean = mean of sample - subset of population Population mean = mean in population

Answer 11

Probability that a population parameter will fall between a set of values 95% CI used Based on 2SD (1.96) 1.96 SD above and below mean = 95% of the SND So 95% confident our sample will be within 1.96 SD of the population mean How accurately our data reflect the true population is dependent on the standard error

Answer 12

Directional - suggests direction of effect Non-directional - does not specify difference/effect Causal - suggests casual inference Non-causal - suggests specific characteristics of behaviour without reference to behaviour One tailed - have specified direction of relationship between variables Two tailed - have predicted that will be a difference but not prediction direction

Answer 13

Small - D = 0.2 Medium - D = 0.5 Large - D = 0.8

Answer 14

Probability of observing the effect as large as observed or larger, if the null hypothesis is true Shows how likely it is that your data could have occurred under the null hypothesis

Answer 15

P<0.05 The smaller the p value, more likely to reject

Answer 16

Parametric: Based on population parameters Assumptions about the underlying population our data is from More assumptions Less universal Distributed data Larger power Non-Parametric: No strict assumptions about the data distribution Can be used when assumptions are met and not met More universal Continuous data Lower power

Answer 17

Scale which we measure DV should be interval or ratio level Populations the sample is drawn from should be normally distributed Variances of the populations should be approximately equal if comparing more then one group No outliers or extreme scores

Answer 18

Devised by William Gosset statistician working for Gyuiness Developed idea of how to make inferences about small differences in population based on differences between small samples Asses how likelihood of obtaining the observed differences between two groups by sampling error Used when want to compare differences in means: Two separate groups One group measured on two occasions Wether one group differs from a specific mean Parametric test - populations the samples drawn from should be normally distributed

Answer 19

Number of individual scores that can vary without changing the sample mean Number of observations made - number of parameters established

Answer 20

One sample t test - N-1 Related t test - N-1 Unrelated t test - (N-1)(N+1)

Answer 21

Repeated/within subjects t-test = used when exploring differences in a within groups design using same participants Independent/between subjects t-test = used when exploring differences between subjects using different participants

Answer 22

Strength of relationship between two variables (r) +1 = perfect positive relationship 0 = no liner relationship -1 = perfect negative relationship Correlation coefficient is ration between covariance and a measure of separate variance When two variables correlated, share variance Square the correlation = get shared variance

Answer 23

Small - R - 0.1 Medium - R - 0.3 Large - R - 0.5

Answer 24

State type of correlation performed, variables correlated, state direction of relationship found Report the test statistic, df, statistical significant Report effect size Comment on direction of relationship

Answer 25

Other measured or unmeasured variables that affect results Partial correlation calculates what the relationship between two variables would be if take away the influence of additional variables

Answer 26

Underlying probability distributions ie normal distributions DV measured at interval or ratio level No outliers Homogeneity of variances Linearity When not met: data may be non-normal, not at required level, outliers, sample size too small, unequal sample sizes if using groups

Answer 27

Parametric: Independent samples t test Related samples t test Pearsons product moment correlation Non-parametric: Mann whitney u Wilcoxon signed rank Spearman's rho

Answer 28

Mann whitney u = alternative to independent samples t - test Wilcoxon signed rank = alternative for related samples t test Spearman's rho = alternative to pearsons product moment

Answer 29

Extent to which an effect found in study was caused by manipulation of IV Attrition - pp dropping out History - events between measurements Sampling - Maturation - pp changing over course Testing and instrument issues - repeating ie order effects Standardised procedures - for both researcher and pp Counterbalancing - avoid order effects Single or double blinding - eliminate research expectations

Answer 30

Degree to which results generalise beyond the experimental context

Answer 31

External: Test-retest ability - correlation of peoples scores at one time and same at later Inter observer or inter rater reliability - ability to which researchers agree in their ratings or codings Internal: Internal consistency of test Participants scoring similarly across multiple items of a construct Most commonly used to measure = Cronbach's alpha - calculation of how closely related a set of items are as a group